1904.] FROM EAST AFRICA AND ZANZIBAR. 95 



and 7 broad in the widest part, but one which was dissected was 

 about twice as large. The colour has become pale green, with a 

 white reticulation on the sides and white stripes on the back. 

 The skin is quite smooth, and there are no tubercles whatever. 

 There are nine or ten pairs of branchiae, of which the last three 

 are quite small. The rhinophores have long raised sheaths with 

 simple edges ; the club is surrounded by six bipinnate plumes. 

 The velum bears at each end a small grooved tentacle of the usual 

 shape and six processes. The two in the middle are simple and 

 smaller ; the other four are larger and branched. 



The jaws are white and membranous in the smaller and probably 

 immature specimen, yellow and corneous in the larger one. In 

 both there are from 20-30 very large blunt denticles, and also 

 undulations near the edge of the jaw, which in the larger specimen 

 sometimes develop into denticles, so that in about half the length 

 there are two rows of denticles and here and there three. The 

 radula consists in one specimen of 47 and in the other of 45 rows, 

 with a formula of about 80+1.1.1 + 80, which rises to as much as 

 85 marginals in one and 100 in the other for a few rows. The 

 central tooth is broad and tricuspid ; the median cusp is taller 

 than the others, but not very pointed ; all the cusps are rather 

 irregular in shape, and have indentations here and there on the 

 edges. The first lateral tooth is large, blunt, and very different 

 from the rest in appearance. The others are hamate. The stomach 

 has a girdle of about 150 horny, yellow, triangular plates of 

 different sizes. 



J do not think that this species can be identified with any of 

 the forms the descriptions of which I have seen *. The color- 

 ation somewhat resembles Tritonia nibra Leuckart and Tr. 

 hawaiensis Pease, but the other details do not coincide. The 

 species differs from the others hitherto found in East Africa in 

 being quite smooth and having no tubercles. 



Marionia arborescens B, 



[Bergh, in Semper's Reisen, xvii. pp. 890-894.] 



One specimen from near Wasin. 



The notes on the living animal suggest that it is the same species 

 as M. ramosa, and say that it differs chiefly in that the bianchife, 

 rhinophores, and processes of the velum are much smaller. The 

 colour appears to have been the same as in that species {i. e. cocoa 

 and green), and it is noted that there was a greenish tinge in the 

 branchife. The back was warty. 



The alcoholic specimen does not look much like M. ramosa. It 

 is rather bent, but the length appears to be about 21-5 millimetres, 

 the breadth 11-5, and the height 9. The back and sides are covered 

 with flat low tubercles and the epidermis comes off in flakes. The 

 dorsal margin is unusually prominent and projects 3"2 mm. It 



* Tn this group as in others I have not access to the descriptions of a few forms 

 by the older writers, e, g. Tr. paJmeri. 



