104 SIR C. ELIOT ON NUDIBRANCHS [May 17, 



divisions, and bears a pair of trifid feathery branchise, one anterior 

 and one posterior. 



The mouth-parts wei'e taken out soon after the specimen was 

 captured, and as preserved consist of a labial armature and radula, 

 but no jaws. It is very likely, however, that the jaws had been 

 lost and were not really absent. The labial armature is miich as 

 in B. digitata. Many of the scales are heart-shaped. The formula 

 of the radula is 21x9-|-l-f9, the number of laterals being con- 

 stant in all the rows. The median tooth has 7-8 very strong 

 denticles on each side of the central cusp, which does not project 

 much. The laterals are rather short and straight. The second 

 stomach is armed with spines as in B. excepta. The liver sends 

 off diverticula into the process behind the rhinophores and all 

 four pairs of cerata. Those which pass into the rhino]3hore- 

 sheath and the fourth pair of cerata are simple, while those that 

 pass into the other cerata are divided into four branches corres- 

 joonding to the divisions of the cerata. 



The simple tentacles of this animal are a sufficient specific, if 

 not generic character, provided they are noi'mal. It is possible 

 that they are a monstrosity, for it is not uncommon in nudibranchs 

 for external processes to remain undeveloped, for example, I have 

 a specimen of Ceratosoma cornigerum in which the characteristic 

 lobes are wanting. But apart from the tentacles, this specimen 

 does not exactly correspond with B. excepta, for instance as 

 regards the rhinophore-sheaths and radula. The median tooth 

 has fewer and sti'onger clenticulations ; the laterals are fewer, 

 shorter, and straighter. 



Pleuroleura alba, sjo. n. 



[Cf. PI. striata van Hass., Eliot in Nudibr. of Maldive and 

 Laccadive Archipelagoes, p. 566-7.] 



Two specimens fi-om Zanzibar. The following are the notes 

 on the living animal : — " Back white with distinct low lidges, 

 longitudinal but not parallel to median line, each "with a yellow 

 line along its summit. The rhinophores stand vei'tically or point 

 forwards and bear longitudinal perfoliations. The base is white, 

 the main part black, the apex truncated and yellow. They are 

 not retractile into pockets, but can be withdrawn under the mantle- 

 edge. They are not very sensitive. The large velum and the 

 mantle are edged with bright yellow. Foot not half the width of 

 mantle. In crawling, the underside of the mantle is applied to 

 the svibstratum over which the animal moves. Length 13 milli- 

 metres, breadth 4 mm." 



The dimensions and colour of the presei'ved specimen have not 

 much altered, though the yellow has become faint. The shape is 

 elongate and tapering. The maximum breadth just behind the 

 rhinophores is 4 millimetres, rapidly decreasing to 3 mm. and 

 2 mm. One striation runs down the middle of the back ; on each 

 side of it are six to eight others, not parallel to it and starting 



