EI.IOT : NUDIHKANCHS FROM TKE INDO-PACIFIC. 2^1 



which bears indistinct triangular thickenings. The teeth are very 

 erect ; those near the middle of the half-rows bear 7-8 denticles rather 

 high up on the outer side ; the outermost are taller and more erect 

 tlian is usual in the genus, and bear 45 denticles on the apex. The 

 innermost are broad, and have a prominence on the inner side, bear- 

 ing 3-4 ridge-like denticles ; the second are also broader than the 

 others, but I could not see any denticles on the inner side. 



This animal clearly belongs to the same group as C/ir. petechialis^ 

 Chr. tumultfera, Chr. pallescens, and Clir. i/iortiaici, and is perhaps 

 best referred to the first of these species, though there are some 

 differences of detail in the labial armature and radula. 



Casella atromarginata (Cuv.). 



Bergh, Journ. Mus. Godeffroy, vi., 1874, pp. 102-9 ; Id.^ Se/npei^s 

 Reisefi, xvii., p. 942; Eliot, " Nudibranchs from E. Africa and 

 Zanzibar, IV.," Froc. Zool. Soc, 1904, vol. i, pp. 399-400. 



One specimen captured in ten fathoms oif Tahiri. 



The living animal is said to have been of a drab tint, thickly 

 mottled with olive-drab ; the sides olive-drab, mottled with white ; 

 on the margin of the mantle was a dark purple edging. This colora- 

 tion is illustrated by a rough sketch, which also shows the rhinophores 

 as purple and the branchicC edged with purple. There is no coloured 

 border round the foot. 



The preserved specimen is contracted longitudinally, with the 

 result that it has become almost circular, being about 35 mm. long 

 and 32 mm. broad. The foot is only 15 mm. broad. The mantle 

 margin is ample, thick, and undulated. The general effect of the 

 coloration is drab, but it is composed of a reddish-brown ground, in 

 which, apparently beneath the skin, are numerous aggregations of 

 whitish dots ; these become yellower near the edge, imparting a dis- 

 tinct yellowish tinge ; the underside is similar, but darker. 'I'he 

 mantle margin is marked by a distinct black line between two white 

 ones. The rhinophores are large and black, the edges of the pockets 

 slightly raised. The branchial pocket is also slightly raised and 

 crenulate, but, as preserved, contracted and closed. The branchial 

 circuit appears to be much larger than the aperture can ever have 

 been, and it is not clear how the plumes emerge ; they are simply 

 pinnate, twenty-four in number, and arranged in a double spiral, each 

 half of which contains eight plumes outside and four inside. 



The buccal cavity is extremely large, particularly the anterior por- 

 tion, and the radula is in comparison small; the formula is 225 x 

 about 65.0.65. The teeth arc colourless, crowded and very small. 

 The cusps are tall, and all the denticles are low down and hard to see. 

 In the interior part of the row there are generally tave denticles, more 



