PART I. GENERAL ACCOUNT 



Fig. 15. Front part of the body of a male 

 Oligobrachia dogieli, A - in dorsal, and В - in 

 ventral view. 



с - cephalic lobe; со - dorsal ciliated band;/"- 

 bridle ; go - genital papilla ; gp - genital aper- 

 ture ; gt - pyriform glands, disposed higgledy- 

 piggledy in two latero-ventral rows ; ms - meso- 

 soma ; mts - metasoma ; ps - protosoma ; s 1 - 

 groove between the protosoma and the meso- 

 soma ; s 2 - groove between the mesosoma and 

 the metasoma; si> - ventral sulcus; tc - ten- 

 tacular crown. (After Ivanov, 1957a.) 



* By metamerism, following Beklemishev, I 

 body of parts similar to one another. 



Athecanephria comparatively large 

 metameric dorsal glandular shields 

 are found along its whole length 

 (Figs. 8, 14); only in the primitive 

 Oligobrachia are they relatively 

 feebly developed (Ivanov, 1957a). 

 In the Thecanephria the post- 

 annular region is furnished with 

 more or less regular ventral trans- 

 verse metameric rows of small 

 adhesive papillae with rod-like 

 cuticular plaques (Ivanov, 1952), 

 while dorsal shields are absent 

 (Figs. 2, 16). 



The single pair of genital aper- 

 tures lies on the metasoma. In the 

 male they are round or slit-like and 

 located on protuberant genital papil- 

 lae, lying ventrally at the bound- 

 ary between the mesosoma and 

 the metasoma in front of the first 

 pair of metameric adhesive papillae 

 (Figs. 9, 15). In the female the 

 lateral genital apertures are situated 

 in the middle of the metasoma a 

 little in front of the zone of 

 thickened papillae (Fig. 10). 



The secondary metamerism of the 

 metasoma 

 From the facts cited above about 

 the external morphology of the 

 different genera and species we 

 may draw several inferences about 

 the origin and development of 

 the metameric adhesive papillae 

 in pogonophores.* We may note 



mean any regular repetition along the axis of the 



