POLYBRACHIA ANNULATA 395 



narrow ridges. The dorsal ciliated band is well developed and continues into 

 the hind part of the preannular region. The metameric region carries 22-28 

 pairs of adhesive papillae, while within the very long non-metameric region 

 five distinct zones may be distinguished with differing densities of adhesive 

 papillae: (1) the adhesive papillae are very small and widely spaced; (2) the 

 papillae are rather frequent; (3) the papillae are sparse; (4) the papillae are 

 mostly on the ventral surface, almost touching each other in places — this is 

 the zone of thickened papillae; (5) the papillae are moderately dense. The 

 lengths of these five zones have the ratio: 12 ! 6 ! 2 ! 1 ! 2. In the females, in 

 which the ova and oviducts may be seen through the body wall of the non- 

 metameric region, the gonads end at the boundary between the third and 

 fourth of these zones, i.e. in front of the zone of thickened papillae, where the 

 boundary is usually very sharp (Figs. 11, 156.F). The girdles are situated on 

 muscular ridges (Fig. 156G), which are separated by considerable ventral 

 gaps wherein lie a few small papillae with rod-shaped plaques. The first 

 girdle, unlike the second, is interrupted only ventrally and not dorsally. In 

 specimens collected from the Sea of Okhotsk the toothed platelets lie in three 

 to four rows (Fig. 156//), while in specimens from the Bering Sea there are 

 usually four to six rows in each girdle (Fig. 1567). The elongated oval platelets 

 are a little narrower in the middle, and the front end is noticeably narrower 

 than the back. Almost a third of the platelet is occupied by the fine teeth of the 

 anterior group, the rest being occupied by the comparatively large, not very 

 numerous, teeth of the posterior group (Fig. 1567). I R specimens from the 

 Sea of Okhotsk the platelets are 15— 18/x long, in Bering Sea specimens 12-15/*. 



The total number of adhesive papillae in the whole trunk is very great, 

 certainly not less than several hundred. The oval adhesive plaques are very 

 small, only 21-28//, across in the metameric region of the trunk, while those 

 lying in the posterior zones of the preannular part are 35-40//, across. The 

 plaques are membranous except for the thickened crescent along the front 

 edge (Fig. 156£). In the postannular section of the trunk the plaques are 

 rod-like, 35// long, placed transversely, a trifle bent, and, for the most part, 

 fringed in front and behind by a narrow membrane. 



A medium-sized, adult female has the following dimensions: length of the 

 tentacles, 16 mm; the fore-part of the body, 3 mm long and up to 0-75 mm 

 broad; length of the metameric region, 6-5 mm; non-metameric region, 

 64-5 mm long; length of the body as far as the girdles, 90 mm; the post- 

 annular region, с 40 mm long; overall length of the body, 130 mm. 



The flat, leaf-shaped spermatophores are like lance points packed with 

 thread-like sperm (Fig. 157). One end of the spermatophore gradually 



