GALATHEALINUM BRACHIOSUM 407 



[2. Galathealinum brachiosum Ivanov, 1961c (Figs. A-F162) 

 Ivanov, 1961c: 1378-1384, Figs. 1-6. 



In 1959 Ivanov received new pogonophoran material collected by an 

 expedition of the Institute of Oceanology of the Academy of Sciences of the 

 U.S.S.R. on board R.V. Vityaz\ to the west coast of North America. The 

 material he received, collected by Dr. Z. A. Filatova in late 1958 and early 

 1959 at stations near the west coast of Canada, U.S.A. and Mexico, consisted 

 of fragments of tubes of various genera and species. Amongst this collection a 

 few comparatively complete animals could be distinguished, forming a series 

 of undescribed species of the genera Galathealinum, Birsteinia, Heptabrachia 

 and Siboglinum. The description of Galathealinum brachiosum given below is 

 a translation of that given in Ivanov (1961c). 



Tubes of this very large species were taken twice by R.V. Vityaz\ first on 

 11 November, 1958 off the coast of Canada and then on 4 December, 1958 

 off the coast of Oregon, U.S.A. Unfortunately, only one tube contained an 

 animal, which lacked the hind part of the body. A series of features in the 

 structure of the mesosoma and metasoma, and peculiarities of the tube 

 indicate its position in the genus Galathealinum. The animal is clearly 

 distinguished from G. bruuni and the very large number of tentacles has 

 suggested the name Galathealinum brachiosum. 



The protosoma and mesosoma are cylindrical (Fig. A162). The latter is 

 three to four times longer than the former. The boundary between them 

 takes the form of a sharp transverse groove which is most pronounced on the 

 sides of the body a little in front of the bridle (Fig. В 162). Between this 

 groove and the bridle the epidermis is covered with numerous wrinkles and 

 forms a pair of latero-dorsal wavy furrows. The epidermis on the ventral side 

 of the protosoma also has a wrinkled surface. In front of the bridle a depres- 

 sion may be observed which gradually broadens into a median ventral sulcus. 

 In the region of the protosoma this is bordered at the sides by two low 

 cutaneous folds which run up onto the sides in the middle part of the proto- 

 soma and then onto the dorsum where they fuse with one another. The 

 broad contracted cephalic lobe is rounded at the tip (Fig. B162). It is divided 

 from the protosoma by a deep dorsal groove which is considerably arched 

 backwards. 



The tentacular crown is very long. It consists of 268 free tentacles disposed 

 in a horseshoe at the base (Fig. B162). Each tentacle bears a few (not more 

 than three or four) densely packed rows of short pinnules. 



The bridle lies in the front third of the mesosoma (Fig. B162). Its keels are 



