CYCLOBRACHIA 365 



ventral rows of small papillae, four or five per row (Fig. J144C). Their small 

 plaques are rod-like (Fig. J144/ 1 ). 



No spermatophores have been observed. 



The dimensions of the body are as follows (mm) : 



Length of the fore-part of the body 1 -5 



Breadth of the mesosoma 0-35 



Length of the metameric part of the mesosoma с . 2 



Length of the whole preannular region 14 



Length of the existing part of the postannular region с 0-8 



Overall length, excluding the tentacles not less than 25 



The ringed and unsegmented tube of H. canadensis is the colour of straw, 

 turning brownish in parts, transparent and lustrous. The front and hind ends 

 are broken off. In the anterior part of the tube the rings are brownish and 

 short, not very regular at first, but more or less uniform in length. Very 

 quickly, however, in the hinder part of the tube, their length becomes 

 extremely irregular. One may frequently encounter very long rings one and a 

 half, two or even three times as long as the tube is wide, though the majority 

 of rings are in fact much shorter (Fig. J144G). The walls of the tube are thin 

 and rather brittle. The overall length of the fragment is 1 18 mm; the diameter 

 near the middle is 0-3 mm. 



In several features, such as the nature of the tube, the number of tentacles 

 and of metameric papillae, H. canadensis recalls H. gracilis. It is, however, 

 distinguished by the larger cuticular plaques, the smaller heads of the toothed 

 bristles of the girdles and the disordered confusion of the papillae in the zone 

 of thickening. Like H. beringensis and H. ctenophora, H. canadensis has two 

 secondary mesosomal grooves. 



Material : one almost complete individual, probably a male, in an incom- 

 plete tube. 



Locality: the north-eastern Pacific off the coast of Canada, near the mouth 

 of Dixon Entrance north-west of Queen Charlotte Island (54° N, 134° W). 



Depth: 2500-2600 m.] 



2. Genus Cyclobrachia Ivanov, 1960 

 Ivanov, 1960c: 6, 24, 106, 107, 114, 199, 215. 



Amongst the new species that I collected while working on board R.V. 

 Vityaz* in Pacific equatorial waters during the summer of 1957, one of the 

 most interesting was Cyclobrachia auriculata. This species was found together 

 with two still undescribed species of ' Siboglinum in a trawl taken at a depth of 



N* 



