REVISE THE GROUP AND TO DETERMINE ITS GEOGRAPHICAL RANGE. 355 



PART III. 



GEOGRAPHICAL DISTRIBUTION. 



The examination of the localities from which the above-mentioned species have 

 In i 11 collected brings out certain points of interest in the geographical distribution 



(if till- gClKT.l. 



The genus Bonellia reaches its northern limit in the species B. vividis, which has 

 b< en found off the coast of Norway whose shores are washed by the Gulf Stream, 

 and its southern limit at Port Jackson, Australia, where the- same species occurs. It 

 lias also been found in the Mediterranean Basin and at the Loyalty Islands. B. suhmii 

 was dredged at a great depth off the coasl of Nova Scotia. 11. minor is Mediterranean, 

 and B. pumicea was found not far from Kxakatoa. On the whole the genus inhabits 

 the warm and temperate seas. 



Echiurus chilensis is found in the Straits of Magellan, E. forcipatus off the coast of 

 Greenland. E. pallasii in the North Sea, North Atlantic, and English Channel, and 

 K. u n id net us iii the Japanese waters. It is thus evident that this genus is a denizen 

 of the colder seas and reaches from the arctic to the cooler waters of the temperate 

 regions of both hemispheres. 



II « mi iii/ia has been found 200 miles north of Cape North and again in the 

 Ilardanger fjord, and is, according to our present knowledge, an arctic and sub-arctic 

 form. 



Saccosomu was found at a depth of 1215 fathoms, about half-way between Norway 

 and Iceland, and is thus again a Northern form. 



Thalassema is of all the' genera of Echiuroids the most prolific in species. Of the 

 21 species described above only one (Th. faex) has been taken from the colder waters, 

 and the temperature of its locality "off the coast of Norway" is much mitigated by 

 the Gulf Stream. Th. lankesteri was found off the Isle of Man, Th. neptuni in the 

 English Channel, and Th. gigas at Trieste. The remaining sixteen species are all from 

 tropical or sub-tropical seas. Five of these occur in the Atlantic, and eleven have 

 been found in the Indian Ocean, the Red Sea and the South- West area of the 

 Pacific. The genus is thus more markedly a lover of the warm water than is Bonellia. 

 The remaining three genera taking their place in the colder temperate or arctic seas 

 of both hemispheres. 



The Zoological Laboratory, Cambridge, 

 February, 1899. 



