1904.] FROM EAST AFRICA AND ZANZIBAR. 275 



25 perfoliations. The branchife ai-e six in number, quadripinnate, 

 low but strong and bushy. The ch-cuit is open behind, and the 

 subcentral anal papilla veiy large. The foot is notched in front, 

 but not grooved; the tentacles are small and adherent. The 

 integuments of the body are thick and tough. 



From the small reddish buccal cone issues a long thin tube, which 

 is twisted into a shape somewhat like S on the right-hand side. 

 The mouth-gland is bilobed. The pei'icardial lamellai are yellowish 

 and not very distinct. Bergh says, " Im Penis wurde eine Haken- 

 Bewaffnung nicht nachgewiesen " ; and I could find none in two 

 specimens. In the thiid there were clearly visible about 1 2 rather 

 irregular rows of thick-set, transparent, hooked spines. 



These specimens seem referable to the forms desciibed by Bergh 

 in the passages referred to, though the descriptions are not alto- 

 gether clear. In the specimens from the Philippine Islands the 

 back was " aufgedunsen knotig " ; in that from Mauritivis, " die 

 Form-Verhaltnissen die gewohnlichen." 



DoRiDOPSis NIGRA (Stimpson) A. & H. 



[A. &, H., Coll. of Nudibr. Molluscs made in India, p. 128; 

 Bergh, S. R. xvi. p. 842, xvii. p. 963 ; id. Danish Exped. to Siam, 

 p. 191 ; id. Beitr. zur Kennt. Japan. iSTudibr. p. 181.] 



Forms which seem referable to this species are among the 

 commonest Nudibranchs on the coasts of both Zanzibar and the 

 mainland. The species, as well known, is extremely variable 

 not only in its colour, Init also in its shape, in the number and 

 form of the branchise, the presence or absence of tubercles, and 

 the configuration of the anterior foot and tentacles, though with 

 regard to the last point it must be remembered that this is the 

 part of the body which is most liable to be obscured and distorted 

 by alcohol. The internal structure of all the varieties seems much 

 the same, and does not present any very remarkable features. 

 The organs are mostly yellowish. The tube which issues from the 

 buccal cone is at first narrow (genei'ally about 1 mm.) and bent 

 considerably, usually on the left-hand side ; it then dilates into a 

 sausage- shaped expansion of about double the width, after which 

 it enters the liver. The mouth-gland is distinct and bilobed. 

 The pericardial lamellte are well developed. The vei-ge is armed 

 with spines of irregular shape. 



The chief varieties are as follows (the texture is in all cases 

 very soft) : — 



(1) Jet-black, without any spots or markings, but white tips to 

 the rhinophores. This form does not appear to be common ; I 

 have only two specimens from Mombasa and two from Zanzibar. 

 The animals are not very large (about 20 mm. long and 10 broad) 

 *nd flattish. The branchite are six. In three specimens the 

 anterior margin of the foot appears to be entii'e and the tentacles 

 are very indistinct. In the fourth both the tentacles and the 

 groove are clear. 



(2) Jet-black, with a brick-red band running round the body, 



18* 



