454 



PART II. SYSTEMATIC ACCOUNT 



spermatophores are 1-5 mm long and 

 0-5 mm broad at the widest part, and 

 in general they are like those of S. 

 grandis, but considerably smaller. 



The mouth of the tube is a broad 

 funnel with coarse stout lamellated 

 walls (Fig. \76A). The funnel and the 

 neighbouring parts of the tube are firm 

 and light brown in colour. Then very 

 quickly the tube becomes straw- 

 coloured and the walls considerably 

 thinner, flexible, and transparent (Fig. 

 176,5). The surface of the tube is 

 smooth and lustrous. In the hind third, 

 the tube, though remaining trans- 

 parent, gradually darkens until it is a 

 dark brown; the walls become much 

 thickened and acquire a considerable 

 rigidity, but are still smooth and 

 lustrous. Finally, near the hindmost 

 end the tube becomes segmented, with 

 segments exactly the same length as 

 the tube's width (Fig. 176C). A pe- 

 culiarity of the tube of S. beklemis- 

 chevi, obvious at first glance when 

 compared with other Pogonophora, is 

 the relatively great length of tube 

 which has a rather large diameter 

 followed by the rapid taper of the 

 hind end. Thus in one female in which 

 the tube was 15-5 cm long the diameter at the front was 1-1 mm and at the 

 hind end 045 mm, i.e. a taper of more than 4(V per cm, and a halving in 

 thickness in less than 15 cm. To all appearances the maximum length of the 

 tube is not less than 30 cm, the diameter across the funnel up to 1 -75 mm, 

 the diameter at the front end, just behind the funnel, up to 1 -4 mm, and the 

 diameter at the hind end 0-2 mm. 



As may be seen in Table 7, the main diagnostic features of S. beklemischevi, 

 as compared with S. grandis, appear to be the considerably smaller number 

 of tentacles and the lesser development of the tentacular spiral and of the 



Fig. 175. Spirobrachia bekkmischevi: 

 Spermatophore. (After Ivanov, 1957a.) 



