WEST COAST HYDROIDS 11 



Thuiaria similis are very plentiful in the Vancouver Island Ke- 

 gion and the north. In this group the centre of distribution is 

 still farther to the northward. Out of a total of 68 species, 57 

 or 83% are found north of Cape Flattery, 49 or 72% being found 

 north of Vancouver Island, and only 22 or 32% to the south. 

 46 are restricted to the north and only 11 to the south. 36 or 

 53% are found in the Vancouver Island Region and 26 or 38% 

 are circumpolar. 



In the PliimularidcE only two, Aglaophenia struthionides and 

 Plumularia lagenifera, are at all wide-spread, but these two are 

 very abundant. INIany species are reported only from a single 

 locality. The centre of distribution for the family, if one can 

 speak of such when the distribution is so scattered, is south of 

 Cape Flatter5^ This is natural as the family is especially a 

 tropical one. Out of a total of 19 species only 10 or 53% are 

 found in the north, while 16 or 84% are found in the south. 

 Only 3 are found north of Vancouver Island. One of these, the 

 only representative of a genus, is reported only from the Aleutian 

 Islands. 12 species or 63% are restricted to the West Coast. 

 The 7 that are found elsewhere have practically nothing in com- 

 mon in their distribution. Aglaophenia latirostris, reported from 

 Brazil, was found off the Oregon Coast and in the San Juan 

 Archipelago. Aglaophenia phnna, reported from Great Britain, 

 Southern Europe and South Africa, was found off the California 

 Coast. Diplocheilus alhnani, reported from the Japan Coast, 

 was found off the Coast of California. Plumularia corrugata, re- 

 ported from Brazil and the Hawaiian Islands, was found in the 

 San Juan Archipelago. Plumularia echinulata, reported from 

 the British Coast, was found in Puget Sound. Plumularia meg- 

 alocephala, reported off Georgia, w^as found off the California 

 Coast. Plumularia setacea, reported from Europe and Florida, 

 w^as found off the California Coast. From such an incongruous 

 list it is impossible to generalize as to distribution. It would 

 seem either, that these species represent the ragged ends of lines 

 of distribution from a centre not yet discovered, or that the con- 

 nections are made along lines in deep water, where up to the 

 present they have not been reached. 



I have very little accurate information concerning bathymet- 

 rieal distribution and still less concerning temperature, not 

 enough in either case to form a basis for general discussion. 



