ASTCHIS BICEPS. 351 



penetrating deeply and having a gaping opening at the bottom. The dorsal edge of the 

 anal plate is indented by shallow notches, which, however, are not quite regular, for on 

 the right six teeth and a flat area at the lateral fissure occur, while on the left four teeth 

 and two flat areas are found. The ventral half of the cup shows three or four shallow 

 indentations on each side of the mid-ventral notch. Between the dorsal and the ventral 

 notches is a median line, but no ridge. The anal plate presents therefore small differ- 

 ences from the descriptions of Malmgren and Arwidsson, but these would appear to be 

 due chiefly to the more distinctly marked notches on the border. A dimple occurs at the 

 base of the caudal plate behind a slight ring, which on this surface is between the first 

 non-bristled segment and the caudal rim. The segmental organs, according to Arwidsson, 

 occur from the seventh to the ninth segment. 



The anterior bristles are for the most part absent in the example, but, so far as 

 observed, they agree with the descriptions of Malmgren and Arwidsson, viz. those with 

 broader and shorter wings and a curved tip, and those with narrower wings and longer 

 tips. The posterior bristles have much elongated slender tips, with opposite spikes. 

 The same kind of bristle (Plate CX, fig. 6) occurs in the posterior third, each 

 bristle having a well-marked curve and the tip forming a very long, delicate, serrated 

 hair. 



The hooks of this form appear to be longer than those figured by Arwidsson; 

 indeed, if his figure (Taf. x, fig. 340) is perfectly typical for Asychis biceps, then doubt 

 remains as to the specific identity of the British specimen. The example from the 

 ' Knight Errant ' (Plate CVIII, fig. 14, and entire in Plate CX, fig. 6 a) differs in having 

 the spikes on the crown less elevated above a line passing from the lower border of the 

 great fang backward, and thus the hook has a different character in that region. The 

 same difference from Malmgren's figure is observed. The smaller teeth on the crown 

 appear to pass on each side of the base of the great fang ; at any rate raised strise are 

 there. The opaque striae running from the crown along the neck to the shaft are much 

 more strongly developed than in the hook shown by Arwidsson. The curvature above 

 the capillary bristles of the throat differs, the neck itself is proportionally longer, and 

 the outlines of the neck to the shoulder are not in agreement. The great length and 

 curvature of the shaft is not fully indicated by either author, so that this point remains 

 uncertain. Arwidsson gives in detail the number of the hooks in each segment, the chief 

 feature being that they appear to increase with size and probably with age. 



The tube is a massive structure of grey mud 7 to 8 mm. in diameter, and at one 

 end tapered to a blunt point (closed). The interior, which has a diameter of 4 mm., 

 is smooth, being lined by a somewhat firm membrane secreted by the glands. 



De Quatrefages (1865) simply quoted this and the previous account from the paper 

 of Sars. 



Arwidsson found the anterior end regenerated, as might be anticipated from the 

 condition of the various examples. Loxosow.se occurred on the anterior segments of an 

 example of 70 mm. from Norway (Arwidsson). 



Reproduction. — Arwidsson notes that female reproductive elements ripen in August. 



The same author 1 (1908) satisfied himself by an examination of the specimen from 



1 c Zool. Anzeiger/ Bd. xxxiii, p. 275. 



