BIRSTEINIA VITJASI 



173 



The non-metameric part of the trunk is characterized by sparse, large, 

 unpaired, lateral, glandular papillae. It was possible to observe in one speci- 

 men that in the zone of thickened papillae there were more than 20 very large 

 papillae arranged on the ventral side of the trunk in a double alternating row 

 (Fig. 9-Ы), and carrying small hoop-shaped plaques on their tips. In this 

 specimen also, the two contiguous girdles of toothed platelets were particu- 

 larly well-preserved. Both of them were interrupted on the ventral side as 

 well as on the dorsal side (Fig. 94i?, C), and behind them lay a small ventral 

 papilla. The toothed platelets, arranged in an irregular triple row (Fig. 94D), 

 measure about 12-18/x in length and are appreciably narrower at the front 

 end. Almost the whole of the front half of each platelet is occupied by teeth 

 which are directed backwards, while the much larger teeth on the hinder 

 part of the platelet are directed forward (Fig. 94£). 



The postannular region is unknown and only males have been seen. 



The tentacles are not less than 4 mm long. The protosoma and mesosoma 

 together reach 4-5-5-0 mm in length and 0-75 mm in breadth. The length 

 of the metameric part of the preannular region of the metasoma is about 

 10 mm. 



The spermatophores of Birsteinia vitjasi are spindle-shaped, greatly 

 elongated, somewhat curved, pointed at one end and almost round in cross- 

 section (Fig. 94.F). On one end the transparent casing of the spermatophore 

 is elongated into a rapidly tapering flat appendix, which bends over at the 

 base. The appendix is prolonged into an extraordinarily long thread whose 

 first part is rather stout and covered with granules of some substance. More 

 distally the thread becomes very slen- 

 der and the granules on it disappear. 

 However tangled the thread may be, 



the 



rather long thickened portion is 



visibly covered with granules of secre- 

 tion. The length of the spermatophore 

 is 0-75 mm, the breadth 0-06 mm. 



The tube is firm and stiff, and its 

 black surface is coarsely granular (Fig. 

 9SA). On the whole it is rather rough, 

 with quite opaque thick walls. Outside 

 a dark layer contains coarse transverse 

 fibres and when this is removed an 

 inner layer is revealed, consisting of a 

 transparent, dark brown substance, 



G* 



4Йщ 



Fig. 95. Birsteinia vitjasi: Tube: A - mid- 

 dle part; В - the same after removal of the 

 outer dark layer. (After Ivanov, 1952.) 



