Gatty Marine Laboratory, St. Andreies. 539 



the rough dorsal surface. The bristled segments are in the 

 large example 46 in number. The frontal bristles of the 

 first pair are very slender and inconspicuous, and do not 

 extend forward the breadth of the body. They are pale, 

 tapering bristles, with long joints and very fine hair-like tips. 

 The dorsal bristles of the second series are still shorter and 

 equally slender. Those of the third series agree, but the 

 ventral have assumed the characteristic stout shafts and finely 

 tapered translucent tips seen in rest of the body (PI. XII. a. 

 tig. 6). They arise from a smooth conical setigerous process 

 with long clavate papillse at the base. The prominence of 

 the ventral division of the foot throughout the body is note- 

 worthy. Between the fourth and fifth segments ventrally is, 

 on each side, a cylindrical or slightly flattened papilla with 

 a smoothly rounded free end, the lower half apparently having 

 a coating of sand-grains. It varies in length in the females, 

 some having long and others short papilla?. 



This form has certain resemblances to the Siphonostomum 

 villosum, of H. Rathke*, though his examples were small 

 and short, probably incomplete. The special characters of 

 the ventral division of the foot and the somewhat stellate 

 arrangement of the papillae around each, when viewed on 

 end, generally correspond. Unfortunately he did not enter 

 into the minute structure of the bristles or figure them. 

 Moreover, it agrees closely with Trophonia arctica, Hansen f, 

 from a depth of 20 fathoms in Magdalena Bay. He, how- 

 ever, describes the dorsal surface as uniformly granulated, 

 and the papillae on the ventral surface as fewer and smaller. 

 On the whole, Hansen's form is smoother. 



There are apparently two varieties of Brada villosa, viz., 

 the shorter northern form and the more elongated type from 

 the ' Knight Errant.' Both have the dense coating of sand- 

 grains which, with the papillae, make the dorsum remarkably 

 rugose, yet there are considerable differences in the shorter 

 northern forms from Fin mark, some of which are much less 

 covered with sand. Both have the ventral papillae exactly 

 in the same position and of like shape, yet amongst those 

 from Greenland and from Finmark the length of these papillae 

 varies, some having short, others long papilla?, so that 

 sexual distinctions in this respect may exist. The number 

 of segments in the shorter northern form is about 23, 

 whereas the specimen from the 'Knight Errant' has 45. 



eitaage zur Fauna Norwegens, p. 21.5, pi. xi. tigs. 11 & 12. 

 t Ncrfske Nordhavs-Exped.. Annel. p. 3!J, pi. vii. figs. 17-20. 



