86 MARINE BIOLOGY OF THE SUDANESE RED SEA. REPORTSon the MARINEBIOLOGY of the SUDANESERED SEA.-XI. Notes on a Collection of Nudibranchs from the Red Sea. By Sir CHARLES ELIOT,K.C.M.G., Vice-Chancellor of the University of' Sheffield. (Communicated by Prof. W. A. HERDMAK,F.R.S., F.L.S.) [Read 18th June, 1908.1 THE Nudibranchs here described were collected mostly by Mr. C. Crossland, but partly also by Mr. J. G. Logan at Suez and in the neighbourhood of Suakim. The collection, though in many respects typical of the hdo-Pacific area, presents several points of interest. The large flat forms (Discodoris, Platydoris, etc.), which are generally so abundant on these shores, are poorly represented, probably because their favourite habitat (the underside of large Jtones on reefs) did not occur in the collecting-grounds. The presence of Goniodoris castanea and Lomanotus vermifonnis (which may be the youug of the Mediterranean species L. genei) is very remarkable, and the question arises whether they are part of the original fauna of the Red Sea or importa- tions through the Suez Canal. Nudibranchs more than most molluscs have a fondness for adhering to the bottoms of ships and probably make consider- able journeys in this way. On the other hand, Tliecacera maculata, Eliot, which is recorded from Karachi (Eliot, in Journ. of Conchol. 1905, p. 242), is hardly distinguishable from 2%.pennigera, which is only known from the British Coast, and the distribution of Lomanotics and Goniodoris may perhaps prove to be similar. The reappearance of Oliola paciJca, Tliorunna furtira, and Plocamopksriis ocellatus is also interesting. These curious forms have hitherto been known only by the descriptions of scanty alcoholic material or by the brief account of Leuckart (1828). I have registered seven new species with cousiderable hesitation. It ib possible that none of them are really new forms, but the characters of the specimens as preserved do not agree with those formulated for any recognized species. Lomanot us cerniiformis and Pleuroleura ylabra ape perhaps immature. Artaclicza verrucosa and Peronodoris detiticulata are very like Bergh's A, Tubitla and PerojLodoris cancellata, but differ in their dentition. Keritro- tEoris lubialis is perhaps identical with Pease's .Doris setosa, but is certainly different from the species of Kentrodoris described by Bergh, and does not entirely agree with the characters of the genus as formulated by him, since it has a labial ariimture. But it agrees even less with the characters of the only alternative genus, A~d21ra,a form with a labial arinature which offers some resemblance to Kentrotloris. It thorefore seeins necessary either to create a new genus for its reception, or to refer it to Ktiitrodoris. I have SIR C. ELIOT-REPORT ON THE NVDIBRANCHS. 57 adopted the latter course. Species possessing n labial armature are found in genera which arc defined as being without this fc:ituro (e. g., Platyloris and Xtcxzcrodoris) ; and though strong plates or real jaws are an iniportant chnractcr, the difference between a labial cuticle with :I vestigial armature mid one which is totally unarmed is very snidl and does not necessarily entail other Rtructural differences. Very curious are the speciinons of Doridopsis ruhra, in which, as testified by the notes on the living animals as well :IS by the condition of the preserved specimens, the pockets of the rhinophores and branchip have almost dis- appeared, causing those appendages to become practically non-retractile. The list of species is as follows :- 1. PLEUROLEURAGLABRA, sp. nov. 2. LOMANOTL-sVERMIFORMIS, $1). iiov. 3. CROSSLANDIAFUSCA, Eliot. 4. MELIBEBCJCEPHALA, Bergh. .i.BOLIDIELLA ORIENTALIS, Bergh. 6. ELYSIAGI~ANDIFOLIA, Kelaart. 7. HEXABRANCHUS SANGTJ1NEUS (Riipprll & ~.enc~i:rrt;. 8. NEMBROTHALINACIFORMIS, sp. nov. 9. TREVELYANASTHIATA, sp. nov. 10, OHOLAPACIFICA, Bergh. 11. PLOCAMOPHERCSOCELLATUS, Leuclmrt. 12. GONIODORISCARTANEA, Alder & Haiicoclr. 13. CHROMODORISDIARDII (Kelaart). 14. CHK. QUADRICOLOR, Riippell. 15. CHR.MACULOSA, Pease. 16. CHR.PALLIDA (Riippell & Leuc1i:trt). 17. CHR. INORNATA, Pease. 18. THORUNNAFURTIVA, Bergh. 19. PLATYDORISINCERTA (?),juv., Eliot. 20. DISCODORISAMBOINENSIS (?), juv., Bergh. 21. KENTRODORISLABIALIS, sp. nov. 22. PERONODORISDENTICULATA, sp. nov. 23. ASTERONOTUSHEMPRICHI, Ehrenherg. 24. ARTACHBACLAVATA, Eliot. 25. ARTACHBAVERRUCOSA, sp. nov. 26. DORIDOPSISRUBRA (Kelaart). 27. DORIDOPSISNIGRA (Stimpson). 28. DORIDOPSISsp. 29. PHYLLIDIAVARICOSA, Lamarck. 30. MARIONIA CYANOBRANCHIATA (ltiippcll c!k Leuckart). 88 MARINE BIOLOGY OF THE SUDANESE RED SEA. PLEUROLEURAGLABRA, sp. nov. 2 = PI. ornata, juv. (For the genue see Eliot : ‘‘ Nudibranchs of Sonthern India and Ceylon,” Proc. Zool. SOC.1906, p. Gi6, ff.) The only notes are : “ Khor Dongola ; nudibranch ; no gills. White with grey mottlings. Eyes halfway up rhinophores.” The preserved specimen is 10 mni. long and 4.3 broad. Its back is mottled with various shades, both light and dark, of grey and greyish green. A row of small black spots runs dong the line of junction between the mantle-margin and the sides of tlie body, and there are others on the sides of the foot. The general shape is as usual in the genus, but the back is quite smooth and bears no ridges or tubercles. Thc rhinop1iorc.s are entirely retracted into clistinct holes about 1 iniii. apart. The tlorsai surface passes through them into the frontal shield without iriterruption. There is a row of pores (apparently cnidopores) on the mantle-edge ; most of‘ them are set in white spots. The jaws are yellow and the edge bears several rows of longish denticles, which are inore than a mere mosaic and become inore numerous on the lower part of the jaw. The formula of the radula for the longest rows is 28 x 18 + 5 + 1+I+ 1 f 5 + 18. The central tooth has a long cusp and about 11 distinct denticles on either side. The first lateral looks rather like half the central tooth and bears 7 distinct denticles on the outer side. The next five teeth gradually assume the ordinary hamate shape, and like the Erst lateral bear 7 denticles on the outer side. The remaining teeth vary from 16 tc 18 in number, and in the majority of TOWS are only 16. They are hamate and quite smooth, no deiiticles being found beyond the sixth tooth froin the rhachis. The outermost teeth are smaller and slenderer than the rest. In order to preserve the single specimen the other organs were not examined. Ten species of Pleuroleura have been described, but the present specimen does not seem to belong to any of thein. It is possible that it may be a young specimen of Y1. ornata, which has a tiiberculate back, a broader radula, and more numerous denticles on the central tooth. Provisionally I describe it as a new species, the principal charactcrs Leing the dentition and the smoothness of the dorsal surface. LOMANOTUSVERMIFORMIS, sp. nov. (See for the genus, Eliot : “Notes on some Britiah Nudibranchs,” Journ. Marine Bid. Assoc. vii. 1906, p. 348, ff.) The notes on the living animal are as follows :-“ Engineer Island, Khor Dongola. A diver brought a large pluniularian hydroid from among coral PIR C. ELIOT-REPORT ON THE NUDIERANCHS, 89 on the reef from which I took many specimens of a small Tritonid. Thej are elongated with a tapering tail, the body being almost vcrrniform and does not contract on killing. The ccrat:i are remarliably small. The colour black with specks of white which are especially aggregated in two bands along tlic sides of the back. Cerata translucent with white tips.” Forty-five specimens are preservccl. The iargrst are 8-10 mm. long, with a niasirnum breadth of 1.5 mm. The colonr remains much as described. Tlic cerata are 20 or more on either side, not foliaceous but concave Gpoon- 4i:iped lamina. The oral veil bears two longish ln-ocewes,and the rhinophorc 4ieaths from two to four. The rhinophores are brown or spotted with bron n ; th(ly appear to bear a few very inconspicuous perforations below the clul). The anterior margin of the foot presents xarious &apes and is probably alterable in life, but is not produced in conspicuou~prolongations in any specimen. The jaws are as in L. genei, with inany rows of denticles or projwtioni nhich have the appearance of a mosaic near the edges. The rnclula i, in tlic confused state common in the genus. There ai-r ahout I? rows, and where the rows can be c1e:wly counted the formula is 9 . 0 .9. The teeth arc’ irw- giilarly denticulate on both sides, nliich as in L. mamio?*citits. The liver appear4 to consi4 of three divisioui and to cnter the stomach hy three ductc,, one posterior and one on cither side. Thr posterior liver ig the Inyest ; it encloses the hinder part of the stonlncli and extends SOIIIP waj- baclclvards. The anterior livers run forward as far as the sicks of thr 1)uccaI 111:1+<. Though branch of the livers cxtend to the bases of the cerata, thy do not send prolongations into them, or into the rhinophore sheaths. Both tl1c cerata and sheaths contain blood-+paces but, not hepatic diverticulx. Tlic genitalia appear to he mature. The wrge is white, large and without any arinature. The hermaphrodite gland is large and appears to contain ril’e o\a ; it lies mainly under the posterior liver, but rives towards the (lord q~rfaceat its sides. The mucus-gland is very large. rllhis species comes very near to L. mwmorutws in size, colour, and anatomy, hut differs in the following points :-(1) The shape is much more elongated and verniiform ; (2) the cerata do not form a wavy curtain but a series of separate and equal projections, a11 on the same level, aucl though all are set 011 the prominent dorsal margin they are not connected by a membrane * ; (:3) the corners of the foot are not developed into distinct prolongations.