SPIROBRACHIIDAE 445 



Ш. Family Spirobrachiidae Ivanov, 1952 



In this family the animals possess numerous tentacles fused together into 

 a tentacular plate, which is then rolled up into a spiral, not unlike a scroll, 

 so that the tentacular crown is asymmetrical. A considerable proportion of 

 the tentacles is supported on a cork-screw-shaped lophophore, which is an 

 outgrowth of the protosoma. 



A single genus: Spirobrachia. 



1. Genus Spirobrachia Ivanov, 1952 



Ivanov, 1952: 384-90; Zenkevitch, 1954: 79,80 ; Zenkevitch, Birstein and Belyaev, 1954 

 67, 68; Hartman, 1954: 184, 185; Ivanov, 1954b: 75, 77, 79; Ivanov, 1955a: 177; Ivanov 

 1955b: 382, 383; Ivanov, 1955d: 173, 174, 176; Ivanov, 1955e: 225; Ivanov, 1956a 

 20; Ivanov, 1956b: 1864, 1868; Ivanov, 1956c: 165, 166, 169; Jagersten, 1956: 238 

 Kirkegaard, 1956b: 186; Abrikosov, 1957: 233, 238; Beklemishev, 1957: 399; Ivanov 

 1957a: 474, 475, 483-9, 490, 492-97; Ivanov, 1957b: 1139; Vinogradova, 1958: 112 

 Dajoz, 1958: 231-3, 236, 237; Fell, 1958: 46; Ivanov, 1958a: 1369, 1370; Ivanov, 1958b 

 1682, 1687, 1688; Ivanov, 1960a: 1528, 1534, 1537, 1539-41, 1549, 1550, 1552, 1561, 1569 

 1572, 1574, 1580, 1581, 1607; Ivanov, 1960c: 6, 11, 18, 20, 23, 24, 25-27, 34-37, 43, 46, 48 

 56, 59, 61, 66, 67, 75, 92, 115, 227, 244, 253-4. 



In the known species the tentacular spiral consists of 39-223 tentacles. 

 The turn of the spire is anti-clockwise, as looked at from in front and starting 

 at the outermost tentacle, and the lophophore is likewise twisted into an 

 anti-clockwise spiral. The protosoma is combined with the mesosoma and no 

 cephalic lobe is separated off. A crack-like median furrow runs along the 

 dorsal side of the mesosoma. The bridle is well-developed. The cuticular 

 plaques in the front part of the metasoma are shaped like bows or hoops and 

 lie on pulvilli. The spermatophores are leaf-like, with long pointed ends. 

 The tube has a rigid, funnel-like mouth. 



There are two species : Spirobrachia grandis and S. beklemischevi. 



Type of the genus : Spirobrachia grandis Ivanov. 



Key for the identification of the species of Spirobrachia 



1 (2) The crown consists of more than 100 tentacles, though from the 

 outside, in ventral view, only 30 may be visible. The keels of the 

 bridle meet ventrally. The hoop-shaped plaques of the metameric 

 papillae are 1 10— 190/x across. The brown-black tube is opaque and 

 up to 2-8 mm in diameter. 1. S. grandis (p. 446). 



