SIBOGLINUM EKMANI 185 



S. pusillum; (iii) the length of the fore-part of the body is 0-6 to 0-8 mm in 

 S. pusillum, whereas it averages 0-9 mm in S. weberi; (iv) the preannular 

 region of the body is over twice as long in S. pusillum as in S. weberi, indeed 

 the whole animal is twice as long; (v) the keels of the bridle are brown and 

 well developed in S. pusillum but colourless and very fine in S. weberi; 

 (vi) the girdles are close together in S. pusillum, but far apart in S. weberi; 

 (vii) the postannular papillae have no adhesive plaques in S. pusillum.'''' 

 (E. С Southward, 1961.) 



Material: about 100 occupied tubes, of which 23 specimens have been 

 examined in detail. 



Localities: Malay Archipelago: Siboga stations 48 (8°4'S 119°4'E— Bali 

 Sea), 52? (9°3'S 119°56'E— Bali Sea), 175 (2°37'S 130°35'E— Ceram Sea), 

 208 (5°39'S 122°12'E— Flores Sea), 212 (5°54'S 120°19'E— Java Sea; here 

 most specimens were taken), 271 (5°46'S 134°E— Arafura Sea), 295 (10°35'S 

 124°27'E— Timor Sea). 



Depth: 462-2060 m.] 



2. Siboglinum ekmani Jagersten (Figs. 97-99) 



Jagersten, 1956: 211-252, Figs. 1-8, Pis. 1-3; Jagersten, 1957: 67; Ivanov, 1957a: 431, 

 434, 494; Dajoz, 1958: 233, 237; Ivanov, 1958a: 1363; Ivanov, 1958b: 1682, 1688; 

 Kirkegaard, 1958: 1086, 1087, Figs. 1, 2; Southward, A. J. and Southward, E. C, 1958a: 

 1607; Southward, E. С and Southward, A. J., 1958b: 627, 628, 631, 632, Fig. 1; Ivanov, 

 1960a: 1524, 1541, 1547, 1559, 1561, 1562, 1567, 1582, 1583, 1606, 1611, Fig. 1466; 

 Ivanov, 1960c: 4, 5, 9, 27, 37, 45, 50, 54, 69, 78, 92, 97, 105, 126, 131-4, 136, 140, 142, 

 145, 174, 188, 196, 265, Figs. 86, 87, 97-99. 



Jagersten based his description of this species upon only two incomplete 

 specimens, which lacked the region of the girdles and the postannular 

 section. He directed his attention chiefly to the internal structure and only 

 dissected parts of the tentacle out of the tube. His description of the appear- 

 ance of the body is thus based on the study of sectioned material. His 

 specimens were collected in 1933, by a Swedish expedition from Uppsala 

 University, in the Skagerrak at a depth of 487-650 m, and included many 

 empty fragments of tubes. 



Not long after Jagersten's account was published, Kirkegaard very kindly 

 presented me with a few individuals of S. ekmani taken by him in 1957 in 

 the Skagerrak at a depth of 640 m (Kirkegaard, 1958). This material made it 

 possible to supplement the description given by Jagersten. 



The length of the dorso-ventrally compressed fore-part of the body is six 

 to nine times the width of the mesosoma, depending upon the degree of 



