364 



PART II. SYSTEMATIC ACCOUNT 



of the 15 large conical papillae of the zone of thickening which are densely 

 packed together in disordered confusion on the ventral side (Fig. J144^4). 



There are two girdles, the first of which has broad dorsal and ventral gaps, 

 while the second is broken only on the ventral side (Fig. J 1445, C). The 

 toothed platelets are arranged in a single row (Fig. J144Z)). As in other species 



10 ji 







Fig. J144. Heptabrachia canadensis: A - zone of thickened papillae in ventral view; В - the region 

 of the girdles in dorsal view ; С - the same region with part of the postannular region in ventral 

 view ; D - part of a girdle ; E - a toothed platelet from the side ; F - a plaque from the postannular 

 region of the trunk ; G - tube. 

 an - girdles ; p - plaques ; pa - papillae. (After Ivanov, 1962b.) 



of Heptabrachia they have a small but well developed anterior group of teeth 

 (Fig. J144£). The platelets are ll-12 /л long. In the girdle region there are 

 several small ventral papillae with plaques, and the large unpaired papilla at 

 the boundary of the postannular region. 



The postannular region has a closely spaced series of transverse metameric 



