1903.] FROM EAST AFRTCA AND ZANZIBAR, 361 



Trip'pa. — Soft, and sometimes spongy or gelatinous. The back 

 is coveied 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 form from the group. 



Halgerda. — The texture is entirely smooth and somewhat stiff, 

 though ridges may be present. In the known species the branchise 

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

 armature, 



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

 minutely granulated. The broad foot is deeply grooved in front, 

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

 into wing-like expansions on each side. The reproductive system 

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

 species, at any rate, the branchife are unusually large, 



Platydoris, — Very flat forms, of a peculiar hard consistency. 

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

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

 forms, A labial armature is rare {PI. variegata). There is a 

 characteristic genital armature of scales beaiing hooks. 



Asteronotus, — Of a characteristic leathery 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 <fe Hancock's Doris osseosa, carinata, apicu- 

 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 

 Platydoris, but the back, instead of being smooth, is marked with 

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

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

 under Prof. Bergh's Pictyodoris, but the generic chai'acters as 

 formulated by him do not include the hard texture and raised 

 reticulate pattern. 



Of the above-named genera, Asteronotits and Kentrodoris, 

 though well characterised and not rare, have not hitherto pi'oved 

 numerous in species. 



1. Archidoris africana, sp. n. 



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

 animal. 



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

 uniform breadth of 2'7, plump and not flat. The colour is a 

 dirty greyish yellow, with traces of violet. The back is covered 

 with tubercles : those in the middle are largest and measure 

 4 millimetres across ; they decrease in size outwards, and are 

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



