422 



PERCY SLADEN TRUST EXPEDITION. 



The Boris ellioli of Alder & Hancock is not a Discodorls but a Platydoi'is (as is 

 clearly shown by the buccal parts and genitalia of the type specimen), and therefore the 

 Discodoris described by Bergh in his account of the Siboga Collection, p. 102, cannot 

 bear this specific name. 



The genus as at present known may be tabulated as follows : — 



D. laliifera (Abraham). 

 D. concinna, A. & H. 



= D. concinniformis, B. 

 (Nos. 1-10 are all from the Indo- 

 Pacific.) 

 D. notha, B. West Indies. 

 D. muta, B. Atl. 

 D. indecora, B. Med. & Atl. 

 D. edwardsii, Vays. Atl., Morocco. 

 D. tristis, B. Atl. 

 D. ? erubescens, B. Trieste. 

 D. branneri, MacF. Brazil. 

 D. ? vonjheringi, MacF. Brazil. 

 D. heathi, MacF. California. 

 D.'i dubia,'&. Smooth. Tasmania. 

 Z). ? egena, B. Smooth. Tasmania. 



10. Discodoris fragilis (A. & H.), 1864. 

 = Discodoris morphaa, Bergh, 1877. 

 See Alder & Hancock, in Traus. Zool. Soc. vol. v. 1864, pp. 118-9; and Bergh on D. morphaa, 

 Malac. Untersuch. in Semper's Reisen, Heft xii. 1877, pp. 536-9, and Challenger Report on 

 Nudibranchiata, 1888, pp. 93-98. 



One large specimen labelled " Lagoon, Diego." It is much bent, but about 90 mm. 

 long and 70 mm. broad. The curious autotomy (which gave rise to the specific name) 

 was beginning when the creature was preserved and a cleft is visible nearly all round 

 the dorsal surface of the body, which would have resulted in the whole mantle-margin 

 being thrown off. I have seen the living animal perform this operation and crawl away, 

 leaving the discarded margin as a complete ring. 



The epidermis detaches itself with great ease and has disappeared from most parts of 

 the dorsal surface. Such fragments as remain are covered with minute, blunt, whitish 

 tubercles and mottled with various shades of grey. The anterior margin of the foot is 

 deeply grooved and the upper lamina is notched, although Alder and Hancock state the 

 contrary. The oral tentacles are cylindrical and pointed. The rhinophores have white 

 tips and project from slightly raised sheaths. The branchial pocket is obscurely 6-lobed. 

 The branchiae are six in number, strong and ample, set in a circle open behind. They 

 are grey but lighter at the tips. 



The integuments are soft and slimy, but contain spicules as described by Alder and 

 Hancock. The membrane which lines the body-cavity has a pinkish tinge. The labial 

 armature consists of two triangular or hatchet-shaped plates which are composed of 



