1904.] FROM EAST AFRICA AND ZANZIBAR. 91 



of a loose mass of long, yellow, transparent i-ocls, irregular in shape 

 and often bent. 



In the two specimens dissected, the radula consists of 30 and 

 31 rows respectively, and the formula of each row is, as a rule, 

 10+1.1.1 + 10 or more rarely 11 + 1.1.1 + 11. The median tooth 

 is squarish, not very broad, and bears, as a rule, five denticles on 

 the anterior edge, but sometimes only four, while in one specimen 

 there wei-e only three denticles in the hinder rows. The first 

 lateral tooth is large and sickle-shaped. The corner of the basal 

 part projects over the rhachidian tooth and creates a false 

 impression that it is an accessory denticle. The remaining teeth 

 are generally ten, but sometimes an additional rudimentary one at 

 the end of the row raises the number to eleven. They are little 

 more than flat squarish plates, decreasing in size outwards. Only 

 the first of them shows some tiaces of a hamate shape. 



All the internal organs are of a deep black colour, which rendered 

 their examination difficult. The blood-gland is large. I was not 

 able to make any satisfactory preparations of the reproductive 

 organs, but the glans seemed to be armed with a dense mass of 

 curved rods. 



I think this form must be identified with JV. crisiata B., of 

 which, however, no specimen has been described, all that is known 

 of it being Semper's drawing and apparently a few notes. But 

 it is also not improbable that it is a variety of iV. nigerrima B., 

 from which it differs externally in little except the absence of 

 any red coloi-ation. The number of branchiae is, as explained, 

 uncertain, but the arrangement shown in Bergh's plate of 

 N. nigej-rima is certainly not that of these specimens. On the 

 other hand, the presence of the narrow labial armature is an 

 argument for identity. 



Nembrotha c^rulea, sp. n. 



Four specimens from Sii Island, near Vanga. No notes on the 

 living animal, except that it was blue and had apparently no red 

 or green mottlings. 



The colour of the freshly-preserved specimens was a fine bright 

 indigo, varying in intensity in different parts. One of the 

 specimens was much lighter than the others and also smaller. 

 The whole of its body and the lighter parts of the other indi- 

 viduals were marked with deep indigo spots. 



The largest preserved specimen is 43"5 millimetres long, 

 18 high, and 12"5 broad. The space from the head to the 

 branchiae is 12 mm. and from the branchife to the end of the tail 

 22 mm., but the tail is longer in this specimen than in the others. 

 The shape is somewhat like that of Ceratosoma without lobes, as 

 the back rises considerably from the head to the branchiae. The 

 integuments are leathery and not at all transparent. The surface 

 is quite smooth, and there is no indication of a mantle-edge. The 

 rim of the rhinophore-pockets is only slightly raised. The rhino- 

 phores themselves are large, entirely retracted, with 25-30 deep 



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