THE 



CANADIAN NATURALIST 



AND 



ON SOME CANADIAN SPECIES OP SPONGILL.E. 



By George M. Dawson. 



The Spongillidce or fresh-water representatives of the marine 

 sponges, though very widely distributed, are not yet known to 

 be represented by a great number of species. It is probable 

 that a systematic exploration of the great North American sys- 

 tems of lakes and rivers might bring many new forms to light. 

 With the exception of S. Loj-dii, Bowerbank, from the sources 

 of the Columbia River, the only Canadian spongilla which ap- 

 pears to have been described, is S. Daivsoni, of the same author, 

 a form inhabiting the St. Lawrence River near Montreal, and 

 other neighbouring waters. 



Having become interested in the examination of a fine species 

 from the Lake of the Woods, obtained in connection with the 

 work of the British North American Boundary Commission, I 

 have been induced, at the same time, to examine a number of 

 other specimens in the collection of Principal Dawson. Among 

 these, and including the Lake of the Woods form, I find four 

 species which I believe to be unde.scribed. These are here de- 

 fined, and though I have not the whole of the literature of the 

 subject at hand, provisionally named. 



The descriptions, from the poor state of some of the specimens, 

 are necessarily not in all cases complete ; but will, I believe, at 

 least serve for the recognition of the species, with the aid of the 

 figures. 



The first spongillas studied — S. fluviatilis and S. lacustris — 

 belong to two distinct types ; and it has been found, on extend- 

 Vol. VIII. No. 1. 



