SIBOGLINUM VINCULATUM 205 



the dorsal side, where, once more, they fuse with each other (Fig. 1065). 

 There is no trace of any glandular tissue behind the bridle. The hind end of 

 the mesosoma is curved both dorsally and ventrally. 



The metasoma is as broad as the mesosoma or, in the male, a little broader 

 even, and the correspondingly broad dorsal ciliated band begins at the front 

 of the trunk (Fig. 1065). The small transverse, oval or rounded metameric 

 papillae have each a pyriform gland visible inside, and the ventral sulcus 

 between them is distinct. The genital papillae of the male are rather large 

 and oval (Fig. 106^4). The zone of thickened papillae was dissected out in 

 the female specimen and found to possess about ten large and ten small, 

 higgledy-piggledy, rounded papillae (Fig. 106jP) with characteristic oval 

 cuticular plaques, some 35-40/x across, with crescentic thickenings along the 

 front edge (Fig. 106G). The two girdles, situated close together, are both 

 interrupted dorsally as well as ventrally. The gap, however, is much wider 

 on the ventral side and very slight on the dorsal side. A few rounded papillae, 

 with the same kind of cuticular plaques as in the zone of thickened papillae, 

 are situated in the region of the girdles (Fig. 106Я, /). The toothed platelets 

 are arranged in two or three irregular rows in each girdle, and in shape they 

 are elongated ovals, with a slight constriction in the middle. The front end is 

 as broad as the back or only a little narrower. A characteristic feature of the 

 platelets appears to be the absence of any anterior group of teeth, so that all 

 the teeth point the same way — sharply forwards (Fig. 106/). The platelets 

 are 11-13/x long. The postannular region of the trunk remains unknown. 



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



Length of the tentacle 

 Length of the fore-part 

 Breadth of the fore-part 

 Breadth of the metasoma 

 Length of the preannular section 



The spindle-shaped spermatophores are greatly elongated and the end 

 opposite the base of the filament gradually tapers to a lancet-like appendix, 



an - girdles; с - cephalic lobe; ca - capillaries of pinnule; со - dorsal ciliated band; dp - posterior 

 group of teeth;/- bridle; go - genital papilla; ms - mesosoma; mts - metasoma; p - cuticular 

 plaques ; pa - papillae ; pi - pinnules ; ps - protosoma ; s 1 - groove between the protosoma and the 

 mesosoma; s 2 - groove between the mesosoma and the metasoma; s 4 - post tentacular groove; 

 i 5 - secondary groove of the mesosoma ; sv - ventral sulcus ; t - tentacle ; vl - lateral cephalic vessel 

 seen by transparency. 



H* 



