19U3.] FROM EAST AFRICA AN'D ZAXZIEAB. 253 



One specimen from Chuaka, E. coast of Zanzibar, under a stone 

 between tide^;. 



The living animal was about 4 centimetres long. The l^ody and 

 appendages were of a unifoi'ui greyish white, with spots of a dull 

 opaque white. The whole animal closely resembled a kind of 

 detachable sea-anemone which is very common at Chuaka, and 

 appears to be sometimes almost free-swimming. 



The alcoholic specimen is 3 centim. long and 1 centim. broad 

 at the widest part, including the cerata. The foot is moderately 

 broad, and has faiily long tentacular expansions in front ; but 

 its most remarkable character is the size and distinctness of the 

 antei-ior groove, which measures 2 millim. across. The upper lip 

 is separated into two parts by a deep cleft. The oral tentacles are 

 lai'ge and very thick. The rhiuophores are shorter and studded 

 with minute knobs, which, in the preserved specimen at any rate, 

 appear not to be set in rings. The cerata are much flattened and 

 almost leaf-like, and the hepatic diverticula within them are 

 ramified. They begin at the anterior end of the large peri- 

 cardial prominence, and are ai'i-anged in about 1 7 gi'oups on each 

 side, each containing about 10 cerata. There are very distinct 

 gaps between the anterior gi'oups, and a broad bare space runs 

 down the middle of the back, but towards the end of the body the 

 cerata are huddled together and continue until the extreme tip, 

 there being no tail. The outermost cerata of all the rows are 

 smaller, and the inner consiilerably lai-ger, but at the base of the 

 innei'most are frequently quite small, some hai'dly larger than 

 tubercles. The genital orifice is below the first group of cerata, 

 and the lateial vent behind the second. 



The specimen was only partially dissected. The jaws are very 

 large, coloiu-less and transparent, with a perfectly smooth edge. 

 The i-adula consists of 32 pectinate teeth, very similar to those 

 of B. mcehii (see Bergh, I. c. pi. Ixxix. fig. 16), with striations 

 under each denticle. They are, however, very much broader, the 

 widest measuring 2 millim., and the denticles are more irregular 

 in shape, being probably worn by use. There are about 150 of 

 them on the broader teeth. Tlie three or four central denticles 

 are generally, but not always, smaller than the others. 



This specimen is clearly referable to Bergh's genus Bceolidia, 

 and the difference between it and the type is mainly one of size, 

 B. vnebii being only 8 millim. long. The similarity of habitat 

 makes one think that this may be merely a full-grown individual 

 of the same species ; and we know so little of the variations which 

 the radula and arrangement of cei-ata may present in Solids at 

 the different periods of their growth, that I am not prepared to 

 reject this hypothesis. Still, the single specimen examined by 

 Bergh appears to have been sexually matui'e, and this being so 

 the two animals each present peculiarities amounting to specific 

 differences : — -(1) In B. mcehii the tentacles are said to be " Jibge- 

 plattet fingerftirmig" ; the cenita begin behind the rhinophores and 

 are set in rows : in B. major the tentacles are stout and round ; 



