128 PART I. GENERAL ACCOUNT 



three to six species inhabiting the one spot. Such an association almost 

 always includes Polybrachia annulata, Heptabrachia gracilis, Siboglinum 

 fedotovi and S. pellucidum, and often also Birsteinia vitjasi, Spirobrachia 

 grandis and Lamellisabella zachsi. 



Two distinct ecological groups of species are found in the Sea of Okhotsk. 

 One group, confined to shallow and moderate depths, is characteristic of the 

 northern basin and includes Oligobrachia dogieli, Siboglinum caulleryi and 

 S. plumosum. The other group of species, characteristic of the southern 

 abyssal region of the Sea of Okhotsk, comprises Lamellisabella zachsi and 

 Polybrachia annulata. It is of interest that there are no endemic species 

 (except perhaps for Siboglinum plumosum) in this sea. It may be that the 

 pogonophoran fauna of the Sea of Okhotsk arose fairly recently by penetra- 

 tion of species from the Kuril-Kamchatka Trench and the Bering Sea into 

 this basin. 



Near the east coast of Japan are found Siboglinum japonicum and S. cinc- 

 tutum. Another variety of this species, S. с var. subtile, has been described 

 from the Malay Archipelago. 



The benthos of the East China Sea still remains almost unknown, but here 

 too new species of Pogonophora have been discovered. Unfortunately little 

 can be written about them because of the fragmentary nature of the material. 



Undoubtedly the seas richest in Pogonophora are those of the Malay 

 Archipelago. In the Flores, Banda, Savu, Ceram, Timor and Arafura Seas the 

 complex of species first named Siboglinum weberi was found — the first known 

 material of the class and long known to science (Caullery, 1914). The 

 Danish Galathea Expedition took Galathealinum bruuni (Kirkegaard, 1956a) 

 in the Celebes Sea; it is probably a characteristic abyssal form of this basin. 

 To the north of the coast of Morotai Island, in the Moluccas, Siboglinum 

 pinnulatum and S. taeniaphorum are found at 500 m depth (Ivanov, 1960b). 

 Siboglinum weberi sensu stricto is known from the Bali, Ceram, Flores, Java, 

 Arafura and Timor Seas. Nine species are known from a single station in the 

 Java Sea and seven from a station in the Flores Sea. Althogether R.V. Siboga 

 took 16 species from the seas of the Malay Archipelago, only one of which 

 (Siboglinum cinctutum) is known from elsewhere and that as a separate variety. 

 Siboglinoides dibrachia has also been taken in the Timor Sea and south of 

 Java. Thus, 20 species in all are recorded from these waters, belonging to 

 at least six genera, and all but two are seemingly endemic (Southward, 1961). 



The Coral Sea, to all appearances, also has a diverse pogonophoran fauna. 

 At any rate, a few trial dredgings and trawlings made by R.V. Vitya£ in 

 the northern parts of this sea yielded a whole series of new species. Here 



