452 PART II. SYSTEMATIC ACCOUNT 



extends behind the bridle (Fig. 174.4). The tentacular apparatus is very like 

 that of S. grandis. The external free edge of the tentacular plate (Fig. 1745, 

 C) is attached to the body in the mid-ventral line, but away from its attach- 

 ment it turns outwards until the distal end of this part of the crown comes to 

 lie on the right side, sweeping around the next turn of the spiral. As may be 

 seen in transverse section the tentacular plate consists of 39-72 tentacles (up 

 to 223 have been counted in S. grandis), and it makes three to four revolutions. 

 The lophophore is much more feebly developed than in S. grandis and makes 

 two or three revolutions in all. The tentacles of the internal turns of spire are 

 arranged in a corkscrew along the surface of the lophophore and, as in S. 

 grandis, the spiral is anti-clockwise, looked at from in front and starting from 

 the outer free edge of the tentacular plate. On the inner side of each tentacle 

 runs a dense line of fine, comparatively short pinnules, which, as a rule, all 

 stick out into the narrow space between the successive turns of the tentacular 

 spiral. 



The fore-part of the body is divided from the trunk by a simple annular 

 groove (Fig. 174Д В, C). The metameric part of the trunk is notable for its 

 considerable length, while the succeeding non-metameric part is short 

 (Fig. 16). The sharply marked ventral sulcus (Fig. 174Д В, C) continues to 

 the end, or almost to the end, of the metameric part (Fig. 16). Usually there 

 are 160-180 pairs of more or less paired adhesive papillae, situated on lateral 

 ridges, but in one individual there were only 120-130. Their metamerism is 

 not perfect; thus, in the individual illustrated in Fig. 16, the 15th papilla of 

 the right side is opposite the 14th of the left side, the 76th opposite the 80th 

 and the 125th of the right side opposite the 128th. The papillae are rounded 

 and vary considerably in size. They bear flattened pulvilli (Fig. 174/)), which 

 in turn bear adhesive plaques. These latter are thin, oval cuticular scales, 

 with a much thickened front edge. In the front part of the metameric region 

 they measure 55-65/x across and in the hind part 75/x, and are thus only half 

 the size of those of S. grandis. The dark-brown thickened front edge may take 

 the form of a bow or hoop. The dorsal ciliated band is broad, with a firm 

 edge (Fig. 174//). The genital papillae of the male are large and protuberant, 

 overlapping the hind edge of the ventral surface of the fore-part of the body, 

 and bear oblique slit-like genital apertures (Fig. 174C). The non-metameric 

 part of the trunk, as stated above, is several times shorter than the anterior 

 part (Fig. 16), whereas in most other Pogonophora the proportions are the 

 reverse. On the ventral side a few scattered papillae may be found in this 

 region, but their exact number cannot be stated because of the vague way in 

 which the metameric part of the trunk turns into the non-metameric part. 





