1904.1 PROM EAST AFRICA AKB ZANZIBAR. 399 



This form has many points of resemblance to Chr. alho-notata B., 

 but the dentition seems different. 



17. ( ?) Chromodoris flava. (Plate XXIY. figs. 8 ct 9.) 



Chromodoris fiava Eliot, Abstr. P. Z. S. 1904, No. 4, p. 15, 

 March 8, 



One specimen dredged on the West Coast of Zanzibar. 



The living animal was 11 mm. long and 3 wide. The colour 

 everywhere, including the rhinophores and branchife, w^as a bright 

 lemon-yellow. Round the mantle-edge ran a blood-red border of 

 ii'regular width . The branchia? were six, simply pinnate, and with 

 few pinnae. The mantle-edge was undulated and ample. The 

 back was flat. The foot projected about 2 mm. posteriorly, and 

 was considerably expanded in front. (From the drawing it 

 appears to be grooved but not notched.) The animal adhered 

 very sti'ongly. The tentacles were hardly visible, being merely 

 two small blunt knobs on the snout. 



The specimen has unfortunately been lost, but I give the 

 figures. 



Genus Casella (Cuv.). 



This small group, though easily recognised by its clearly ma.rked 

 and much undulated mantle-margin, is not distinguished fi'oin 

 Chromodoris by any features of importance, and there is no 

 sufficient reason, except convenience, to maintain it as a separate 

 genus. The chief character is the aforesaid undulation of the 

 fairly broad mantle-edge, and the outermost teeth of the radula 

 are smooth instead of being denticulate on the apex. Bergh 

 recognises three species, all from the Indo-Pacific. 



Casella atromargixata (Cuv.). 



[Bergh, Jour. d. Mus. Godeffroy, vi. 1874, pp. 102-9; id. S. R. 

 xvii. p. 942.] 



One specimen from the West Coast of Zanzibar. 



The notes describe the living animal as long and tapering, with 

 a flat back and a mantle-edge only slightly projecting but 

 elaborately wrinkled at the sides. The foot hardly extended 

 beyond the dorsal ai'ea. The general colour was brown, with 

 numerous small grey spots, but towards the edge of the mantle 

 became first yellowish and then greenish. The mantle-edge itself 

 was defined by a very distinct black border. The rhinophores 

 were black, with a grey line on the edge of each lamella. The 

 gills were black and grey, set in a double spiral and kept in motion. 

 The animal was about two inches long, and, in spite of its sombre 

 coloration, a handsome creature. 



These charactei's and colours are well preserved in the alcoholic 

 specimen. The mantle is narrow both at the sides and behind, 

 a,nd somewhat expanded only over the head. The bi'anchise are 

 arranged in a double spiral meeting in front but leaving an open 



