552 SIR CHARLES ELIOT. 



gills are 12 (eleven in Bergh's specimen), arranged in an incomplete circle, the vacant space 

 in which is filled by the anal papilla. The two median gills are separate, the others con- 

 nected into two groups, five on each side. A strongish labial armature of bifid hooks. 

 Radula without thickenings or rhachis. Innermost teeth somewhat irregularly denticulate on 

 both sides. Outermost very irregular in shape. 



Gen. Ceratosoma Ad. and Reeve'. 



This genus is easily recognized by its extraordinary shape. The body rises upwards 

 fi-om the head so that the branchiae are much higher than the rhinophores. Near the 

 branchiae are two side lappets and behind them a long dorsal process. There is a round 

 frontal veil, a narrow mantle edge and a narrow foot prolonged into a tail of nearly the 

 same length as the body. In their essential characters these animals resemble Chromodoris". 

 There is a labial armature of hooks: the radula has no central tooth but numerous hamate 

 laterals which are sometimes denticulate. The tentacles are retractile : the branchiae simply 

 pinnate : the reproductive system unarmed, and as in Chromodoris there is no true stomach. 



I have seen numerous specimens of Ceratosoma polyomma alive in East African waters. 

 They are sluggish and generally found among seaweed, where they make no attempt to 

 hide themselves. They have a strong, disagreeable odour. The colour varies from green 

 to chestnut-red and there is also some variety in the shape; one specimen had neither the 

 lateral nor the dorsal lobes. 



11. C. trilohatum Gray. 



Two specimens from S. Nilandu Atoll, Maldives, 30 /. The animals as preserved are 

 quite white, except for a slight bluish tinge at the end of the dorsal process. They are 

 hard and of a peculiar waxy appearance. This is not the coloration of the specimens 

 previously described, but the species seems to be really characterized by the back being 

 relatively less steeply inclined than in others, by the thick mantle edge and frontal veil 

 and by the thick, rounded and somewhat indistinct lateral lobes. They resemble fairly well 

 Gray's figure {Figures of Molluscous Animals, PI. 67, fig. 14) of Doris trilohata. The largest 

 specimen is .5'7 cm. in length and 1'5 in breadth across the lateral lobes. The strong 

 rounded tail is 3' 2 cm. long and the dorsal process 1 cm. The foot is a long narrow groove. 

 The mantle edge, lateral lobes and frontal veil are all thick and indistinctly marked off 

 from the body. The tentacles are retracted: the mouth is a narrow vertical slit between 

 them. The labial armature consists of two light yellow plates, rather soft and composed 

 of little hooks. The radula contains about 70 rows: in each row were numerous hamate 

 teeth bearing a single denticle on each side of the naked rhachis. The back is quite 

 smooth ; immediately below the dorsal process lies the small branchial opening, which con- 

 tracts even further within. The rim is smooth and hardly raised. The branchial apparatus, 

 which is retracted into the lowest depths of the cavity, is rather large and it is a wonder 

 how it can even emerge from so small an opening. The branchiae appear to be 14 in 

 number. In front are two, quite separate. At the sides are six united together and some- 

 times bifid so that it is hard to say how they should be counted. The posterior ends of 

 these two lateral groups turn inwards. 



' Bergh, S. R. Heft x., xvii., and Supp. Heft i., aud in - Some species of Chromodoris {e.g. Ch. Semperi) have a 



Nudibranchiata of CluMenger. dorsal prominence behind the gills which recalls Ceratosoma. 



