216 PART II. SYSTEMATIC ACCOUNT 



10. Siboglinum caulleryi Ivanov (Figs. 3, 8, 10, 12, 14, 85, 111-13) 



Ivanov, 1951: 740, 742, Fig. 1 (as S. weberi); Ushakov, 1953: 179 (as S. weberi); 

 Abrikosov, 1957, 234, 236, Fig. 3; Alvarado, 1957b: 495; Ivanov, 1957a: 434, 440-6, 456, 

 458, 459, 490-3, 495-8, Figs. 6-13, 59; Ivanov, 1957b: 1127-44, Figs. 1, 3-10, 12, 14; 

 Brunet and Carlisle, 1958: 1689; Dajoz, 1958, 231; Ivanov, 1958a: 1363, 1369, Fig. 10; 

 Ivanov, 1958b: 1682, 1688, 1689, Fig. 2; Ivanov, 1958d: 1; Ivanov, 1958e: 1070-86, 

 Figs. 1-4, 6, 8; Manton, 1958: 748-51, Figs. 1-22; Ivanov, 1960a: 1528, 1529, 1537, 1541, 

 1542, 1545, 1548, 1549, 1559, 1562, 1566, 1567, 1592, 1600, 1608, 1609, 1612, Figs. 1390, 

 1392, 1394, 1396, 1403, 1411, 1413-14, 1418, 1448, 1451, 1453-8, 1461, 1463-4, 1468, 

 PI. VI; Ivanov, 1960c: 5, 11, 22, 27, 28, 34, 44, 50, 53, 55, 91, 93, 94, 96, 105, 108, 127, 

 145, 153-8, 160, 196, Figs. 3, 8, 10, 12, 14, 22, 30, 32-3, 38, 67, 70-7, 81-2, 85, 87, 111-13, 

 PI. I. 



The cylindrical fore-part of the body is six or seven times as long as it is 

 broad (Figs. 3, 8, \\\А У В, C). The groove dividing the protosoma from the 

 mesosoma runs straight across the ventral side, but on the dorsal side it 

 curves strongly backwards to meet the dorsal ends of the keels of the bridle. 

 The mesosoma is three times as long as the protosoma. The comparatively 

 large, more or less conical, cephalic lobe is not delimited from the protosoma 

 and it is pointed at the tip. The slender and extraordinarily long tentacle 

 (Fig. 3) is furnished with very small pinnules arranged in a single longitudinal 

 row, with slight traces of a tendency to form two rows (Fig. 111/)). The 

 proximal part of the tentacle for a considerable length is free of pinnules. In 

 the living animal the tentacle is coiled into a tight corkscrew, which sometimes 

 persists to a greater or lesser degree in preserved material. [This is probably 

 true of all species of Siboglinum, when the animal retracts into its tube and is 

 not feeding; but in life the tentacle can protrude from the mouth of the tube 

 to a considerable length, and probably this always happens when the animal 

 is feeding — D.B.C.] 



The bridle lies in the front half of the mesosoma and at the middle of the 

 anterior section of the body. Its very slender cuticular keels are situated on 

 slightly raised cutaneous ridges (Fig. 11Ы, В, C), and the ventral ends are 

 fused together in the mid-line, but dorsally they just fail to meet each other. 

 In some individuals a narrow transverse glandular patch of integument, 

 whitish in colour, may be detected just behind the bridle. The trunk 

 (metasoma — Figs. 3, 8, III А, В, C) is divided from the mesosoma by an 

 oblique groove and in its front part it is perceptibly flattened dorso-ventrally. 

 The narrow, dorsal ciliated band begins a short distance behind the start of 

 the metasoma. The pronounced ventral sulcus is bordered by rounded, 

 metameric papillae which lack cuticular plaques and possess instead a 

 glandular character (Figs. 3, 8, 11Ы, C). Their metamerism is incomplete 



