Polyzoa of Queen Charlotte Islands. 43 



bathe the shores of the Queen Charlotte Islands they evi- 

 dently find a congenial home and are finely developed. 

 There is nothing to show that they are unfavourably affected 

 by the change of climate. Of these northern forms only one 

 seems to reach the Mediterranean ; a few are widely distributed 

 in the British seas, while the rest are pretty much confined to 

 Shetland and the north-east and north-west coasts. In Prof. 

 Verrill's ' Check-List of the Marine Invertebrata of the 

 Atlantic coast, from Cape Cod to the Gulf of St. Lawrence ' 

 (1879) thirty-one species are included which occur in the 

 Queen Charlotte Islands, and of these nineteen are Arctic ; so 

 that the results of the northern migration have been much the 

 same on both sides of the continent. 



The remaining species obtained by Dr. Dawson constitute 

 a somewhat miscellaneous company. They include a small 

 group of cosmopolitan forms which occur in almost all lati- 

 tudes, and are expected, as a matter of course, to be present 

 wherever Polyzoa are found. Such are Microporella ciliata 

 (perhaps the most widely distributed species in the class), 

 iSchizoporella hyalina (which almost equals it in this respect), 

 Smittia trispinosaj and perhaps Hii^pothoa distans. A few 

 species occur which have been found as far up the Pacific 

 coast of America as California and Vancouver Island, but 

 which are not known as Arctic forms. These are no doubt 

 southern species which have travelled so far northwards. 

 Indeed the Queen Charlotte Islands are, in a remarkable 

 degree, the meeting-ground of northern and southern forms. 

 Memhranipora Eosselu, M. tenuiroslris, Crihrilina radiata^ 

 ScMzoporella Cecilii, S. sanguinea, S. torquata, and Dtastopora 

 suborhicularis are essentially southern. 



Seventeen species are common to the Islands and Australia, 

 and of these thirteen are also European : nine of them occur 

 in the Arctic seas. Two have only been found, so far, in 

 Australia and the Queen Charlotte Islands [Porella marsiqnum 

 and Mucronella sjnnosissima) . Lepralia cleidostoma has oc- 

 curred in these two localities and off the coast of Florida. 



It may be noted here that of the whole number of Queen 

 Charlotte Islands species only nine are not also European. 



Some of the ascertained facts respecting the distribution of 

 the Polyzoa are sufficiently perplexing, and we must wait for 

 a larger accumulation of data before we may hope to explain 

 them satisfactorily. The way in which certain species are 

 strewn, as it were, at haphazard over the surface of the globe 

 is a difficulty of which the solution is not apparent. We must, 

 I think (as I have suggested before), make large allowance 

 for the agency of man, and of currents, floating weed and 



