104 SIR c. ELIOT ox xuDiBRAXcns [INfay 1 7, 



divisions, and bears a pair of trifid f eatheiy branchise, one anterioi 

 and one posterior. 



The mouth-parts were taken out soon after the specimen was 

 captured, and as preserved consist of a hibial ai'mature and radula, 

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

 lost and wei-e not really absent. The labial armature is much as 

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

 of the radula is 21x9-|-l + 9j 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 sjiines 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 rhinophore- 

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

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

 ponding to the divisions of the cerata. 



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

 not generic character, provided they are normal. It is possible 

 that they area monstrosity, for it is not uncommon in nudibranchs 

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

 a specimen of Ceratosoma coi-nigemm in which the characteristic 

 lobes are wanting. But apart from the tentacles, this S2iecimen 

 does not exactly correspond with B. exce2)ta, for instance as 

 regards the rhinophore-sheaths and radula. The median tooth 

 has fewer and stronger denticrdations ; the laterals are fewei', 

 shorter, and straighter. 



Pleuroleura alba, sp. n. 



[Cf. Fl. 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 ridges, 

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

 line along its summit. The rhinophores stand vertically 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 withdiuwn 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 substratum over which the animal moves. Length 13 milli- 

 metres, breadth 4 mm." 



The dimensions and colour of the pieserved 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 



r22i 



