1902.] NUDIBRANCHS FROM ZANZIBAR. 63 



a little below the tip. Above the mouth ai'e two short, slender 

 erect tentacles. Behind them are the i-hinophores, which are 

 considerably longer and more slender than the cerata : they 

 bear about eight bracket-like semicircles, which alternate with 

 one another, so that thei'e is not a complete circle round the 

 rhinophore ; at the base of each i-hinophoi'e is a black eye-spot. 

 The foot is i-ounded in front and the corners are not pi'oduced 

 in tentacle-like expansions (PI. VI. fig. 13). 



The body is translucent and colourless (the viscera being white) 

 with a few blotches formed of opaque white dots. The cerata 

 are also translucent, except at the rings, which are opaque white ; 

 they bear a few orange spots or streaks. There is a long orange 

 streak on each rhinophore. 



The jaws are small and the masticatory edge is finely denti- 

 culate. The radula is short and uniseriate. Each tooth is shaped 

 like a horse-shoe and bears on its antei'ior margin one large 

 denticle with six small ones on each side (PI. VI. fig, 12). No 

 trace of armature was discoverable in the reproductive organs. 



In many characters, in the disposition of the cerata, the 

 rounded anterior margin of the foot, and the buccal parts, 

 the animal appears allied to Cratetia ; but it differs in two points, 

 the rudimentary perfoliation of the I'hinophores and the rings 

 round the cerata.' The latter peculiaiity is, so far as I am aware, 

 unrecorded among the Solids, but it almost entirely disappears 

 in specimens preserved in alcohol, and it is therefore possible that 

 it may i-eally exist in other genera which have been described 

 from such specimens. 



DuNGA NODULOSA, gen. et sp. nov. 



This animal is fairly common on colonies of SerUdaria. The 

 body and tail are both long. The cerata are easily detached and 

 have then some power of independent movement. They are 

 carried very erect in the living animal and are set in transverse 

 rows varying from four to six in number. Behind the last 

 transverse row is a clump of smaller cerata, also of varying 

 number. Probably the caducous character of the appendages 

 has something to do with these variations. Each transverse row 

 consists of ten cerata, gradually increasing in size from the 

 outside to the centre, the two middle ones being much largei- 

 than the others. The outer cerata are of the ordinary cylindi'ical 

 shape ; the middle ones are swollen and ovate, but terminate in a 

 fine point. At the top of the broad part and at the base of this 

 point ai-e eight knobs. The rhinophores are very long and simple. 

 The tentacles are moderately long, and the anteiior angles of the 

 foot are produced into processes of about the same length. The 

 foot is narrow and without markings. The length varies from -5 

 to 1'2 cm. 



The coloration is very variable and I'anges from clear light 

 yellow to purplish brown. These difierences may be partly due 

 to two different colours of the liver diverticula seen in the 



