BIRSTEINIA 169 



Locality: the southern part of the Barents Sea at a number of stations in 

 the area 69°-75°N 35°-40°E. 

 Depth: 170-325 m. 

 Substratum: sand or sandy mud.] 



3. Genus Birsteinia Ivanov, 1952 



Ivanov, 1952: 377, 388, 389; Hartman, 1954: 184; Ivanov, 1954b: 72, 76; Zenkevitch, 

 1954: 76; Zenkevitch, Birstein and Belyaev, 1954: 68; Ivanov, 1955a: 177; Ivanov, 1955b: 

 382; Ivanov, 1955d: 173, 174; Ivanov, 1955e: 224; Ivanov, 1956b: 1864; Ivanov, 1956c: 

 165; Jagersten, 1956: 238; Kirkegaard, 1956b: 186; Abrikosov, 1957: 236; Ivanov, 1957a: 

 435, 439, 468, 490-3, 495; Vinogradova, 1958: 112; Dajoz, 1958: 231-3, 235, 237; 

 Ivanov, 1960a: 1573, 1607; Ivanov, 1960c: 5, 19, 23, 24, 27, 31, 37, 60, 92, 105, 114, 120. 



The protosoma is continuous with the cephalic lobe, but divided from the 

 mesosoma by a deep groove. The 12 free tentacles, arranged in a horseshoe 

 at their base, have double alternating rows of pinnules. The preannular 

 region of the metasoma has numerous metameric papillae provided with 

 cuticular plaques, a proportion of which lie on pulvilli. The postannular 

 region and the girdles themselves are unfortunately unknown. The sperma- 

 tophores are spindle-shaped. Two erroneous statements were made in the 

 original description of this genus (Ivanov, 1952). Firstly, it was stated that 

 the base of the tentacular crown was in the form of a ring, whereas it is, in 

 fact, horseshoe-shaped, and, secondly, a peculiar segment — the brachyo- 

 phore — was described at the base of the tentacles; when I re-examined the 

 material I found that this was absent (Ivanov, 1957a). My former opinion 

 (Ivanov, 1952) that Birsteinia belonged to the Polybrachiidae has likewise 

 turned out, after reinvestigation, to be incorrect. By the arrangement and 

 development of the coelomoducts of the protosoma Birsteinia must take its 

 place in the Order Athecanephria (Ivanov, 1957a), whereas the Poly- 

 brachiidae appear typical representatives of the Order Thecanephria. 



The genus Birsteinia has only one species. 



Type of the genus : Birsteinia vitjasi Ivanov. 



/. Birsteinia vitjasi Ivanov (Figs. 93-95) 



Ivanov, 1952: 377-9, Figs. 7-12; Ivanov, 1954b: 72, 76, Figs. 3, 8; Zenkevitch, 1954: 

 76, Figs. 5, 9; Zenkevitch, Birstein and Belyaev, 1954: 68, Fig. 10; Ivanov, 1955e: PI. 

 LXV,Fig. 3; Kirkegaard, 1956b: 186, Fig. 4; Abrikosov, 1957: 236, Fig. 6; Ivanov, 1957a: 

 439, 468, 491, 492, 495-7, Fig. 59; Dajoz, 1958: 233, 235, 237, Fig. 6; Vinogradova, 1958: 

 112; Ivanov, 1960a: 1537, 1538, 1541, 1546, 1552, 1608, 1612, 1620, Fig. 1399; Ivanov, 

 1960c: 5, 19, 22, 92, 96, 105, 120, 210, 263, Figs. 17, 87, 93-95. 



