1903.] FROM EAST AFRICA AXD ZANZIBAR. 361 



Trippa. — Soft, and sometimes spongy or gelatinous. The back 

 is covered with tubercles which themselves bear smaller promi- 

 nences or filaments. A labial armature is occasionally present 

 (Section Fracassa). Some species have special glands set round 

 the buccal mass, and the sides of the head connected with the 

 foot, but it does not appear to me that the absence of these 

 characters ought to exclude a foi-m from the gi-oup. 



Ilalgerda. — The textui'e is entirely smooth and somewhat stiff, 

 though ridges may be pi-esent. In the known s^iecies the branchiae 

 are scanty. No member of this group is known to possess a labial 

 armatui'e. 



Kentrodoris. — Broad, soft, and flat, with the dorsal surface 

 minutely granulated. The broad foot is deeply gi'ooved in fi-oiit, 

 and the upper lip, which is notched in the middle, is developed 

 into wing-like expansions on each side. The I'eproductive system 

 is sometimes armed, and accessory organs are present. In some 

 species, at any rate, the branchiae are unusually large. 



Flatydoris. — Yery flat forms, of a peculiar hard consistency. 

 The back is minutely granulated and rough to the touch. The 

 foot is naiTow. The branchial pocket is stellate in the known 

 forms. A labial ai-mature is I'are {^Pl. variegata). There is a 

 characteristic genital ai-matvire of scales bearing hooks. 



Aster onotus. — Of a characteristic leatheiy consistency. The 

 back is quite smooth in texture, but bears lumps and ridges. No 

 labial or genital armature. 



Sclerodoris. — This new genus is proposed for certain forms 

 which appear to have never come into the hands of Prof. Bergh, 

 though I think Alder & Hancock's Doris osseosa, carinata, ajncu- 

 lata, and tristis (" Notes on a Collection of Nudibr. Moll, made in 

 India," Trans. Z. S. vol. iii. 1864) should be referred to this 

 genus. It is characterised by having the same hard texture as 

 Flatydoris, but the back, instead of being smooth, is mai'ked with 

 various ridges and depressions. In the known species there is no 

 labial or genital armature. I should wish to bring my iSclerodoris 

 under Prof. Bergh's Dictyodoris, but the generic characters as 

 formulated by him do not include the hard texture and raised 

 reticulate pattern. 



Of the above - named genera, Asteronotics and Kentrodoris, 

 though well characterised and not rare, have not hitherto proved 

 numerous in species. 



1. Archidoris africaka, sp. n. 



One specimen mai-ked " Chuaka, shore." No notes as to living 

 animal. 



Alcoholic specimen 5 centimetres long, 1"6 high, with a fairly 

 luiiform breadth of 2*7, plump and not flat. The colour is a 

 dirty greyish yellow, with ti'aces of violet. The back is covered 

 with tubercles : those in the middle are largest and measure 

 4 millimetres across ; they decrease in size outwai'ds, and are 

 quite small at the mantle-edge. The top of each is lighter, ^^^ 



