WEST COAST HYDROIDS 9 



those on the West side. It is rather gratifying to find that only- 

 four species are found common to the north and the south of 

 Vancouver Island that are not found in the Vancouver Island 

 Eegion, because this indicates that however scanty the collection 

 is, it must be fairly representative of the whole coast. 



Since the number of species has become more extensive, the 

 conclusions of some earlier authors that for a great number of 

 species, the distribution occurs along meridional lines from a cir- 

 cumpolar centre, seem to be more fully corroborated. Of the 45 

 species common to the East and West Coasts of North America, 

 no less than -10 or 897c are also found either in Europe or in thfe 

 Arctic Regions generally, distributed as follows: Total 45, Gym.. 

 7, Camp. 23, Sert. 13, Plum. 2 ; Common 40, Gym. 6, Camp. 21, 

 Sert. 12, Plum. 1, while the total number of species common to 

 the West Coast and the South Pacific is inconsiderable. 



Taking up a more particular comparison of forms along the 

 Coast itself, though there is a fairly general distribution in the 

 different groups, the centre of distribution for the coast varies to 

 a large extent. 



Of the Gymnoblastic forms 31 have been found along the whole 

 coast, but the distribution is much scattered. This may be ac- 

 counted for by the fact that most of the collecting has been done 

 by men that are not hydroid systematists and the soft yielding 

 nature of the Gymnol^lastic forms makes them less noticeable to 

 such collectors, than the more rigid, and in general more con- 

 spicuous, CaljTptoblastic forms. Corroboration is given to this 

 from the number of Gymnoblastic forms reported by Dr. Torrey 

 from the California Coast. He, being familiar with such forms, 

 was able to find a relatively large number. No one species has 

 been found over a large area, although some are quite abundant 

 in certain localities. Cape Flattery divides the group quite ac- 

 curately into two equal parts. 20 species liave been found north 

 of that point and 20 south of it. 11 are restricted to the north 

 and 11 to the south. These to the north are evenly divided be- 

 tween the Vancouver Island Region and north of it. 9 are found 

 in the Vancouver Island Region and not north of it and 8 are 

 found north of that Region that are not found in it. 3 are com- 

 mon to the two regions. 12 species are eireumpolar but none are 

 found common to the South Pacific. 



Among the Campanularian forms, in the Family Campanular- 



