.<. 0 1 1 t,he Ma~(!riira~i (:ellus BB!/nl./i,/cincl~s, ivit.11 Dewriptiotr uf a INW

Species. Ily I.SAI:KLLA GOKLWY, D.S(:., l'h.U., P.X.S. From the Ilepartnient of' Zoology, British Museum (Ka,Ltura.l Histwy).

[1Zcrcivcd A u g i ~ s ~ 2:1, 193.7 : Kcad E'otruilry 1: l!K<ti,l

(Text- figurcs 1-7 .)

Kccetit~ly ii. i ~ t i i t Lor of p t w s fivm Mdeira. tvurc: nciit. to [.lie Britiuh i%l~i.;cuin by Mr. E. U . Boulenger, Direttor of the Aqnariittii of' thc Zoological Socicty. Them specimens provcd t u belong to t,he rather uiicomnon genus Rlqnchocinetes Mhe-Edwards, the previorisly ki io~ . i i species of which are recurtied from thc Indim and Pacific Ocems. Tlie Atluntic specinlens, BS

mas to be expected, represent. a new- species which differs from the Indu- Pacific forms i n having the rostrum incoinpletely articulated with the carapace. All the females are carrying eggs at, various stages of development, and i is the qreciniciis reached London about t'hc 10th of July it is probable that tlic height of the breeding season is in h y and June. One other ovigerous female from the same locality had been presenfed to the British Museum by Seiior A. Nunes in the summer of 1927. On August 21st, 1935, two additional specimens were presented by Mrs. E. B. Carter *.

This species, which is described below, is a rather striking form with its humped abdomen and its vivid red a.nd white coIour scheme (text-fig. 1). It ie desirable to have more specimens, captured at various seasons of the year, in order to determine whether or not the older inales acquire external iriaxillipods and first peraeopods of great size as in H. typus and, most probably, also in It. durbanensis and R. hendersorLi. I think i t unIikely that species of' this genus are hermaphroditic, but mueh more abundant material of fhe various species would he required to finally settle this point (see p. 81).

I have re-examined specimens referred bystebbing and by Balss to R. typw, and, as they proved t o differ from hhat species both as regards the branchial formula and the sexual pleopods of the male, I have had to give a new name to each form. As the number of species is thusdoubled, I have extended the key to the det'errnination of the species given by Kemp (1925, p. 263).

It gives me great pleasure to express my thanksto Mr. BouIenger, Mrs. Carter, and Sefior Nunes for sending the specimens of R. rigem ; t.o Dr. Kemp, F.R.S., for placing the ' Discovery ' material a t my disposal ; and to Prof. L. A. Jagerskiold, Naturhistorisk Mudets, Goteborg, for sending specimens of R. balssi on loan.

The drawing of the entire unima1 is the work of Miss 0. F, Tassart.

Family R H Y N c H o c I N E T I D x. Genus RIIY~CHOCINETES We-Edwards.

Kemp, 1926. Records Indian Museurn, Calcuth, xxvii. pt. iv. p. 263 (rcferenceu to previous papers on hhe genus).

* Mrs. Carter informs me that these a d the specimens from the Zoological Society mcre caught in fiiie-mosheil lobster-haps ill shalluw water, and that t h y can be obtained wily in summer ; this may indicate t,hat the species haa a welLmarIiod seasoid migration.

~CHYSCHOCIXETES RIGENS, sp, 11. (Text-fip. 1, 2, 3, 1, & 5, e , ) XateriwZ.-Yontinha Bay, 1 ovig. 9, presented by Seiior A. I Y unex. 2 58, 7 ovig. @ (including holotype), present'ed by t'he Zoological Society

1 $, 1 ovig. 9, preuent'ed by Mrs. El. R . C:art,er. Ilescription of hdotype (9 ;

of London.

l.=HO mm. npproximatelyj.--'llie curupucc: is covered with finc, inconspicuous vertical striz. Thc lower limit of the orbit is continuous nit.h the tip of the aiiterinal spine ; the supraorbitd spine is absent and the pterygostoniia.1 angle is rounded. Thwe are three teeth behind the articulation of the rostrum, . the second niuch nearer t o thc first than to the third [text-fig. 2, u ; in the holotype t,Iie t.hird iu larger than t.he second tooth).

The rostrun~ is long, slender, strongly curved upwards, and reaches well beyond the ant,ennal sealc. The lower border is armed with eight t,eetJi uniformly graded in size, direction, and distance from each other (text-fig. 2, a) . There are two large dorsal teeth on the proximal third and two small teeth near t,he apex. The articulittion of the rostrum [shaded in figure) extends downwa,rds almost to t,he strong lat.eral ridge, which iu continuous wit'l.1 the orbital border ; only it very limited upward and downwud movement is thus possible.

The eye is large m d almost, globular, the cornea is niucli wider than thc: st,alk, arid its greatest diameter is not quite one-third t.he dorsal 1cngt8h of t.hc carepare.

SntennuZe.-The antennn1a.r peduncle reaches a 1it.t.k beyond the second d o r d toot,h on t.he rost.runi propor ; the stylocerite is long, lateral t.0 t,he basal segment, acut,ely pointed anteriorly, reaching the distal articulation of the ultimate pediincular segment. On the ant.erior margin of the b a d segment, near the outer angle, is a large lobe, ending in a minute spine which does not rea,ch the distal end of t,lie penult.imat.c segment (text-fig. 2, c). The

The circular oculsr spot is distinct, in contact with the cornea.

N A C R U R A S (ZENITS RHYNCITOCISETRS. 7 7

outor anterinuLw Ragellmi ih someu lint thickened and wtosc in the proximal two-thirds, nliichh readies the first subapical spine of the rostrum ; tlip distal third is thread-like and fine (text-fig. 1) .

The antennaE srnle is not quite three timer as long as wide, and ronsitIerabl57 narrowed distally ; the tormirial spine 011 the miter margin evtcnds slightly beyond the cnd of the lamella (text-fig. 2 , d ) . The flagr~lh~m, w l i c ~ ~ Pomplete, is about as long a8 the body, rostrum inrlirdccl.

Text-fignre 2.

a.

Rhynchocineetes ~igens , sp. n. Paratypo. a, rostrum showing lateral ridge and incomplete articulation with carapace ; b, abdornina

somites 4-6 ; c, antennuler peduncle ; d, antennal scale. (Setce omitted.)

Mudibbs.-The mandibular palp is three-joinhd, as represented in text-fig. 3, a, b ; the short basal segment has a prominent lateral setose lobe, the second is expanded somewhat on the margin next the incisor process ; the terminal segment is broadly ovate and heavily setose. There are five or six teeth on the incisor process ; the moIar process differs considerably in the right and left mandibles, as represented in text-fig. 3.

The third maxilliped scarcely reaches the tip of the antennal scale ; the idtimate is approximateIy half as long again as the penultimate segment,

Text-figure 3.

Rhynchocinrtes r i<p?s , sp. n . Pxrntypr a , left mandible from two different asperts (terminal palpal argmant

omittrd in nne) ; b, riglit mandible.

is 1.6 times as long as the carpus, which is also rnrinatc ; the palm is nearly 2.5 times as long as wide, and twice as long as the fingers. The immovable finger ends in three long movable corneous spines ; the dactylus is hoof-shaped, with about twelvP similar spines (in two graded wries) set trxnsveraely aerosq the apex.

The sncoiid ~ i c ~ w o p o d i s i ttore sleiicler, a i d j n s t csceecla the i~iit'eniial petI1111plc. Thc inertis is cwirinte, s~i1xyii;rl to the chela' ilwl tile ischiurn, with wtiic.Ii IrLtter it ix ,joinctl hg n very oblique articulation. The carpus i s approxiiria.tely one-third larigvr than the chela. Rntl scveii tinws as loiig as wick. The iinmovuble finger has three t.ertninaI (~orneo~is spines, the clactylus nhniit eight.cen, in two gradcd series.

The third p~rmpod exceeds t'he a,ntannal scale by the Iengt,h of t.he dactylus, n-hicli bears two c.on,spicuniis spinw in arldit.ioii to tlw terminal ctlnw. Thc meriis i s scvcn tiiiies as long as wide a n d has seven spines on thc ontcr siirfme, two median near the diata.1 articulation, t.\m 011 or near t,he ventral margin, and three on the proximal half slight'ly d o r d t.o the median line. Thc ischiurn and carpus havc each two spines. The propodus ia six t,imes as long as the dactylus, with, on t.he v e n t d margin, a few spinulcs, the dish1 four or five of which gradually increase in size.

The fourth perizopod reaches the end of the wale and has the same number of spines on the outer surface.

The ,lifth permpod reaches the middle of the scale and has four spines on the mcrus, one on the carpus.

The abdomen is covered with fine st 'rk similar to t,hose on the mrapaco. There is a tooth on either side, immedia'teIy above the posterior margin of the ylcuron of somites 4 a.nd 5 (text-figs. 1 & 2 , b ) . The large pleuron is separated from t'he second somite by e fine but distinct suture ; there is a deeper oblique suture on the plcuron of the first m d third somites respectively (text-fig. 1) . The sutiires between segments 1-3 have been omitted intext-fig. 1 .

The telson is nearly as long as t,he endopod of the uropod, tapering, and a.rmed wit,h three pairs of dorsal spines on the dista.1 half, t,hree pairs on t.he terminal margin.

P1eopods.-The endopod of t'he first pleopod is much larger than the exopod and has no appendix interna (text-fig. 4, a). The exopod and endopod of the second pleopod are subequal, and there is a large appendix interna (text-fig. 4, f),

The branchial formula differs from that of 22. @pus * in one respect, namely, tltat t,he a.rthrobra.nch corresponding to t'he fourth pereopod (i. e . , on XIII.) is absent. The to td number of art'hro- and pleurobrenchs on IX.-XIV, is t,hus ten instead of eleven. An epipodite ia present on a11 the peraeopods with the exception of the last.

Nule.-The male specimens, measuring 86-89 mm. in total length, are rather more slender t,han the females. They exhibit no noticeable sexual differences in the chelipeds and external rnaxillipeds.

The endopod of the first pleopod bears a large appendix interna with a fold at the base of the na.rrow lateral project,ion (text-fig. 4, d) . I am not cert,aiii whether or not this is a suture t. Thc specimens, like some of t.he females, must have died in the aquarium, and the distal part, of the endopod is much swollen and rather distorted. The pleopod of the inale present,ed by Mrs. E. B. Carter is probably nearer to t,hat of the living animal ; here tho endopod ir folded along t.he orit.er and the distal half of the inner margins (text-fig. 5, e ) .

The appendix inasculina is rnt'her shorter than the appendix interna of the second pleopod (text-fig. 4, e ) .

There is a fine suture on the second abdominal somite at the upper edge of the enlarged pleiiron, ils in the female ; the srit.ure on t.he pleuron of the third

* I have examined specirncns in the British Museum collection. Milne-Edwarcjs

t See also p. 85. gave the number of gills as iiint? on each side (1837, Hifit. Nst. Crust. i i . p. 383 ; Paris).

80 DR. ISARELLA GORDON ON TIIE

Text-figure 4.

8 es.

K!kynehoeinele$ rigens, sp. n. Paratypes. n , normal first pleopod of female, sets omitted ; b and e, rathor abnorrnnl endopod of first

pleopod of female, with appendix interna ; d, endopod of first pleopod of male (distal portion ccdematoua) and appendix interna of another specimen further enlarged ; e, appendix interna and appendix masculina on ondopod of second pleopocJ of male ; j anti q, appendix int,orna on enriopod of snconrl plenpod of fernate.

TRE XACRURAN GENTJS RHY-UCJIOCINETES. 81

wrnite is almost tmneversc n t d Iess conspicnous, that on the first pleuron is

Ahmrmuliti~s.-One fernah IMS i t conspirnour nppciidix intertia on the ~ ~ i c h p o d nf ~ a c h first plwpod (text-fig. 4,6) but, no imcc of an nppeiidix niasciilina

Text-figure 5 .

;lhhLLI]t (cf. text-fig. 1).

a.

d.

Bhynchocinetes typva M.-Erlw., (I. 78-84 rnrn.). a , rostrum ; d, chela of first perseopod.

e.

u

RhyncRocinetes durbaxensi8, nom. nov., J (l.= I7 mm.). 6, rostrum ; c, chela of larger first permpod.

Rhynchocinetes rigpas, sp. n. e, first right pIaopod of male ; the ondopod is folded along the outer margin and on the

inner margin distal to the appendix intern&.

on the second pleopod (text-fig. 4,~). Another female has a vestigial appendix intern& on the endopod of the first pIeopod on the right side (text-fig. 4, c ) , that on the left being normal. In two of the three females of R. b&& examined (p. 87) each first pleopod has a large appendix interna. It is,

PROC. ZOOL. S0C.-1938. Ti

1 think, very unlikcly that tllcst. specics Lire ~icrrnaI)hrotlitic, but fiiturp workers might do well to look fiirtlicr into tlic cpcstion *.

Borradaile (1917, Trans. Linn Snc. ( 2 ) Zool. xvii. 3. p. 352, pl. liii. fig. 2) mentions the prcseriw of an apprnc1i.i interiia on the first plcopod of Uro- cariddla ; later Kemp (l!)i!2, Rec. I td hlns. xxiv. 3, 1) 112) pointcd out thdt this was a characteristic of the male onlv, anti tha t in this respect t l i ~ genuq was probably unique amongst Cariden. Sincae then <in appendix interna has hemi described in thc ninlc of other C‘aritknn qenrra, c. g., Cnridiiza (Gordon, 1933, J. Linn. SOC. London, Zoo1 xxxviii. 11. 3.34, fig\. 2 arid 3) and ICh!/nrhocincfPs. In d n r h stioides there is ~ i i appendix intcr-na on the first pleopod in ho/h SP.YPS

(Gordon, 193.5, J. Linn Ror. xxxix. p. 346, figs. 26 n and 27 ( I ) . l?emnrXs.-Thc rostml formula varicy wlne\\llat, r . q., the Yentrd series

of teeth varies from 7-1 1 and. 1x1 one inbtiltice, the fourth tooth in the secie.; is absent. In one fcinale there j, i l single (hr.sal tooth on the rostrum proper, in front of the articulation : the Imgest female has three dorsal teeth near the apex.

The nuniber of spines on the outer surface of the three walking-legs also varies, especially on the nierucl, there being 3-7 on the first, 3-6 on the third pair ; there is often a single spine on the carpus.

The Iateral sutures on the anterior ,ibdomiiial somitcs ~ o u l d 8ccm to be characteristic of adults of the geniis Rhynchorinetes, althoiigli they have not hitherto been described t. In R. t!ypus and H. balssi I find that they are present on the first and third pleura of the female and the third pleuron of the male ; that on the second somite is wanting in both sexes. In R. mgulosus there is a suture on the third pleuron of a male specimen measuring 50 mm. in total length ; in two small males, each not cxceeding 24 mm. in length, there appears to be no trace of it. Of R. hendersoni I have only examined the male mentioned by Kemp (1925, p. 270) ; this dried specimen has the usual suture on the third pleuron, the second pleuron on each side is slightly bent at the place where the suture mould occur, but I am not sure that a suture is present.

R. rigem differs from all previously described species in having the rostrum incompletely articulated with the carapace and provided with a pair of strong lateral ridges. This is an approach to the Hippolytide and Palaemonida?. The gill-formula has not been mentioned in the descriptions o f all the species.

R. rigens is most nearly allied to El . hendersoni Kemp (1925, p. 265), a much smaller form from the Indo-Pacific. The main differences between the two species are tabulated below.

Such sutures are unusual in Csridea.

R . hendewmi. R. rigens.

Total length. 35-40 mm. 8697 mm Rostrum. . . . . . . .

Antennular peduncle.

Strongly curved in female, not in the male.

No lateral ridge ; articulation with carapace complete.

Distal spine on basal segment far exceeding periultimatc scgmcnt, and subequal to spinose tip of stylocerite.

More slender ; strongly curved upwards in both sexes.

Strong lateral ridge ; articulation with carapace incomplete.

Distal spino on basal segment not exeeding penultimate sag- ment and far shorter than spinoso tip of stylocorite.

.-. . - -. - . .

* See Berkoloy, 1930, Contr. Cttnad. Biol., Toronto 6, pp. is-163, for sex reversal in There is never

7 The posterior part of the suture on the third pleuron o f R. wguloaus is indicated

Pandalids ; fig. 14 shows the gradual transformation of tho first pleopod. any trace of an appendix masculina in the abnormal females of Rityn~hoeinetea.

in fig. I , pl. Ixxxix. of MrCulloch’spspcr (1909, ftcr:. Aiwtr. 31us. vii. , Sydney).

83

First perZenpot1 .

First pleopod A simple, narrow appendix in- ternit on endtipod ; esiipotl less taporing distally and three times as long a$ wide (at base).

of male.

80-97 IH111.

2. Does not, reach end of antenna1 scale ; tinctylus with 10-12 rnc,vabln corneous spitics, in two graded series, ti11 apex ; immovahlc finger with t h r w sirrii1a.r spines.

3. As in '2.

P spines in ncldition to termiiral C~lSW .

d tooth on oither side of fourth and fifth sornit.es, above pos- terior. margin of plouron.

A suturc 011 socorid sorniie, at upper edge of pleuron, in both SCKCS.

A broad, folded qpendix in- terzia on endopod : csopod more narrom-cd distally and fire times as long as wi(lc (at base).

RHYNCHOCINETES TYFUS Milne-Edwards. (Text-figs. 5 , a, d ; 6, a, b.) Rhynchocinetes t y p s Kemp, 1925, pp. 263-265. AdditionaE record.-Valparaiso, in harbour, 10 m. ; 15. x. 31. ' Discovery '

Expedition, R.R.S. ' William Scoresby ' : 1 ovig. 9. Remarks.-The type-species of the genus differs from all subsequenWy

described species in three respects: (1) It has an art,hrobranch at the base of the fourth perampod (on XIII.) in addition to those on XI. and XII. (2) The endopod of the first pleopod of tho male has the proximal inner angle projecting far beyond the inner margin of the peduncle (text-fig. 6,a). (3) The appendix masculina is longer, not shorter, than the appendix interna (text-fig. 6, b ) *.

RHYNCHOCINETES DURBANENSIS, nom. nov. Rhynchocinetes typus Stebbing, 1917, Ann. Dnrban Mns. ii. p. 27, pl. vi.

(Text-figs. 5, b, c ; 7, c, d.)

(nee R . typw M.-Edw.),

* That of H. lieniler.soi?i is shorter than the appendix interna in the dried male from Fiji.

(i*

DR. ISABELLA GORDON OX THE

Text-figure 6.

C.

Rhynchodneles iypu-s M.-Edw., $.

a, endopod of first pleopod, Showing variation of the appendix interna ; b, Becond pleopod.

Rhynechocdnetes mqulosus Stimpson, 8 (1.=50 mm.). c, endopod of first pleopod ; d, second pleopod.

b.

d.

Remarb.-One of the specimens described by Stebbing is in the British On comparing it With males of R. typus from Chile, Museum Collection.

of xpproxinia,tely t,he sil,rtlc total lciigt'h, it provcd to bc1c)iig in a tlistinct form, differirig frorii thc type-species as indicated in thc following table :-

A. t y p s , ci".

fig. 6, a). Seuuzul plei,puci . Appciidix interna t i a i w w , nliortei.

t l i m appcrdix masculina ( t o x t - fig. 6, 6).

fig. 6, a). Seuuzul plei,puci . Appciidix interna t i a i w w , nliortei.

t l i m appcrdix masculina ( t o x t - fig. 6, 6).

RHYNCHOCIXETEb Rl~C17LOSTJS ~tinrpori. Rhytynekocindes ruqulouzcs Kemp, 1925, p. 263 ; p. 289, fig. ti (in part). Hemarh-In Kemp's figure (1). 269, fig. ti) tlir appendix interriit of tlic

first pleopod appears to be coinposed of two segments. TJh , I think, i:, due merely to a foldirig of the distal p r t of the appendix (as iti text-figs. 6, (1 & 7, n , for example) ; ulien the nppuriclix is straight, a h in text-fig. 6, r , it is SWIA to consiat of a single segment R. rugulusus differs froin all thr other speries in having a blunt lobule near the middle of the outcr border of the endopod of the first pleopod ; it is present in each of the thee nialev examined.

In the specimen from Y e w Zealand, described by Borradaile (10163, Eritiih Antarctic (' Terra Nova ') Exped. 1910, Zool. iii. 2, p. SS), I have been unable to find the arthrobranchson XI. arid X U * ; tlieseareprescnt in n much smaller specimen of R. rugulosus from Australia. I therefore rcfer this specimen to R. Iralssi. It is highly probable that all specimens recorded from New Zealand (whether under thc name of 11. typus or of R. rugulosus) mill prove to belong to this form without arthrobranchs on XI. and XII.

(Tcxt-fig. t i , c, d.)

RHYNCHOCINETES BALSSI, nom. nov. Rhglnchociwtes typ'us Balss, 1922, in Carl Skottsberg's Kitt. Hivt. of Juan

Rhynchocinetes typus Borraclailo, 1916, British Antarctic (' Terra. Nova ') 1 $!

(Text-fig. 7, a, h.)

Fernsndez and Easter Island, iii. p. 331 (holotype the ovig. 3 re-examined),

Exped. Zool. iii. p. 85 (referred by Kcmp, 1925, p. 264, to 11. rugulosus). without ova.

* Seo footnotr, p. 87.

a. .IJ C. d.

b.

Ehynchocinetes baZssi, uom. nor., 6 (1. 32-33 mm.). a, first pleopod ; b, socotid pleopod.

Rhynchocineh durbanensis, nom. nov., $. c, endopod of first pleopod ; d, socond pleopod.

A&;tional record.--' Disrovery ' ColIection, Station 935, 34" 11' 5." S., 172" 08' 5" E., to 34" 11' 9" S., 172" 08' 5" E., 7 . viii. 34, 80 m., 1 ovig. 9.

~?emarks.--On re-examining three of the specimens from Masatierm dc- xtaribed by Balss, kindly Ierit by Prof. J&gerskiiild, 1 was surprised to find that 110

art.hrobrwllcbhs :we prrsctit8 011 XI.-XlII.*. In R. t:ypu.s d l tlirec arthrobtaiichs arc prcserit, while in iizwt othcr s~~ecie,s only the Iwt . one is inissiii,g.

As poiiited out by Kernp (192.5, p. 264) tlic: specimens agree in most rcspccts with R. rngu loms rat,lier tliaii 1vit .h R. iypus. The rostriii formrila, as well a s tlic reliitivt: 1engt.h~ of t . 1 ~ stFloceritt: iititl distal spitic 011 the basal imt,eiinuIiir segment., ;igtc:e quite \\.ell with R. r . r t g u / o s ~ ~ ~ . In larger specirnetis the stylo- ccrit,e is rnucli loliger thnri the distal spine :tnd may reach the distal eiid of t,hc ultiiiiai,tv segirieiitm ; in sinall spetitnetis the atyloccritc and dish1 spine arc siibcqual, the forrrior only reidiing t o or slightly heyom1 thc distal cnd of thc penukiiiinte segrtwnt.

In neither form do the inales show any Irucc of hypertroplij? of t.be external ma xillipeds or first poraopods. The sexual ~~lcopods of R. Bnbssi are represented in text-fig. 7 , a & b ; t h r c is no lobule on the outer margin of t’lie endopod of t’lie first pleopod, srtch i t s is characteristic of R. W ~ U Z O H M (t.ext,-fig. 6, c ) .

The ovigerousfenialc from Masnticrra (totztl lengtmh=41 mm.) and t.he ‘ Terra Nova ’ spccinieii each posse s ii \r-cll-dcveloped a,ppendix iriterna on t,he first. pleopod. In t’he ‘ Uiscoverj- ’ spwimm t’liis appendix is absent (see p. 81).

I have referred the New Zealnnd specimens in the . Terra Nova ’ m d ’ Uiscovcry ’ collections to R. brrlssi pro\-iaionally because of tlic agreement, in tho br;tllclliid formula. It is l o be hoped that in tlie nciir future mom m;l,teTiitl will bu available frotii each of t h e t.wo widely separatctl localities.

Kcy to the Uetc;rmi?iatiox o j the Species of Rhpchocineteu.

The species fall into t.mo well-defined groups, as shown by Kemp (1925, p. 263) ; his key is given below in an ext,eiided and somewhat modified form :- I. Two tcoth or1 ~ ~ r a p ~ : ” behind rostra1 artirdittion ; a

strong supraorbital spine preswt ; lower limit of orbit defined by an angulation below which is the antenna1 spine ; no tooth on oither side oifourth or fifth abdominal tramites above postorior edge of pleuron; [no lttteral suture on second abdominal sumite ; rostrum a-ithout lateral ridgo and articulation with carapace complete].

A. Rostrum with 6-8 teeth on upper border near apex and

1. Basal sognicnt of artennule with distal sphe much longer than styloceritc aid reaching almost or quite t o distal end of ultimato segment ; roat.rum very dcop; first persopods of large inalo cqiial, chela with a fringe of silky hairs on dactylus and distal part of palm ; appendix rnuardina longer than appendix interna ; an arthrobranch on XIXI. . . . . . .

2. B m l segment of antcnriule with distal spine scarcoly longer than stylocerite and reauliirig dish1 end of penultirnrtto sagmorit ; rostrum mom slcnder ; first perseopod of large malo very unequal y, larger chela with short curved dactylus without fringe of silky hairs ; appendix masculha shorter thuii appendix interna ; no arthrobranch 011 XIII. . . . . . . , , , . , . , .

17-21 on lower border.

R. t ypm Milne-Edwards.

K. durbanenuis, nom. nov. ---_- -+

* Since t,liis paper went to press Prof. Jagcrskidd sent me other five specimons, all Iii une of there thore is a, vestige

It is also probable that a similar rudiment Terra Nova ’ specimen and that it has

I do not, t.hereforo, f e d justified in separating R. baIssi from the other

males, of the srnall species R. balssi (from hIitsat.ierra). of an art.lirobranch 011 XI. on the loft sidc only. was origindly present on tho right side of t,he been detached. species and erecting a new genw for it.

t Only ono malo oxemined.

88 'THE MACRLTRAN UXNGS RHYNCHOCINETES.

13. Hostrum uith 3-6 teeth on upper border near apex and 10-13 on lowor bordcr ; [appendix masculiria shorter than appendix intern& ; basal segment of' antennule with distal spine reaching almost or quite to distal orid of penultimate segment, and, in adults *, considerably shorter than t,he stylocerite 1.

1. 4 blunt lobule on outer margin of eridopod of first pleopod; carapace and abdvmon in adults finely but conspicuowly striate ; no arthobranch on XIII.

2. No blunt lobule on outor margin of ~ ~ ~ i o p d of first plaopod, which is entirG ; carapace and abdwneii smooth or with excoedingIy fine strire ; no arthru-

11. Three teeth on carapace behind rostra1 articulation ; no supraorbital spine : 1OWQr limit of orbit continuous wit,h antenna1 Spine ; a tootli on either side of fifth, or fourth and fifth, abdominal somitos above posterior odga of pleuron; [rostrum wit.h 2 or 3 teeth on upper border near apex and 7-11 on lower border; carapace and abdomen feebly striate ; no arthrobranch on XIII. i j

A. A tooth on either side of fifth abdominal omite ; ros- trum without Iateral ridge and articulation with car&- psco complete ; b a d segment of anteririulo with distal spine reaching almost t o middle of ultimate segment and nearly as long as styliJcodte ; first perzopod of' female with t=i e~rneous nail at tip of each finger . . . .

U . X tooth on either side of fourth and fifth abdominal somites ; rostrum with strong lateral ridge and articula- tion with carapace incomplete; basal aogment of antennulo with distal spine minute (not roaching distal end of penultimate aegmant), stylocerite reaching distal end of ultimate segment ; first parseopod in both sexes with three long, narrow, movable corneous spinus on fixed finger and 10-12 similar spines (in two graded series) on dactylus .............................. I?. riprr.~, sp. 11.

h'. I U ! / ~ ~ O U U S Sti inpso~~.

branchs on XI.-XII..t ......................... I t . balsui, uwn. nov.

H. Imcclersotsi Kemp.

* In small specimens the stylncerito is shorter and may be subequal to the distal spine

t Seo footnote on p. 87. 1 Tlie branchial formula is not given by Kainp ; on relaxing the dried specimen in t.lio

on the basal segmcnt ; in adults it may reach the dislal end of the ultimate scgment.

Brit. Mus. Call., it proved to have no arthrobranch on XlII .