52 ON THE LAND AND FRESH-WATER 



TJnio Canadensis of Lea is supposed, as yet, to be peculiar to 

 Lower Canada. It is, however, a species but little understood 

 and may be detected in the northern New England states. A 

 Valvata found by Mr Bell at Matanne, and Little Lake Matape- 

 dia, and perhaps new to science, I have never found in the New 

 England states. It resembles so closely a depressed variety of 

 Valvata piscinalis of Europe, that I hesitate to separate it from 

 that species. The whole of the land and fresh-water shells of Lower 

 Canada, with these two exceptions, are also found in New England. 

 But in endeavouring to generalize on the geographical distribu- 

 tion of the mollusca in Canada, we cannot afford to ignore the 

 additional evidence afforded by our knowledge respecting other 

 groups of animals, and of the sister science of botany. It will be 

 more philosophical to consider the geographical distribution of 

 plants and animals generally, than to take any one isolated group of 

 animals for special consideration and study. 



Mr. Woodward, in his excellent " Manual of the Mollusca," has 

 considered that the peculiarities of the mOlluscan fauna of Canada, 

 are so well marked that we are justified in considering the 

 Canadian as a distinct Natural-history province. This view I 

 have endeavoured to show, in a previous paper, is not borne out 

 by an increased knowledge of facts. The naturalist, looking on 

 the map of Canada, observes an irregular peninsula stretching 

 down to the southwest, and at its furthest extremity running par- 

 allel to the state of Ohio. From that state it is divided by Lake 

 Erie, which at this point varies from thirty to sixty miles in width. 

 Cutting off this peninsula (say from Georgian Bay in Lake 

 Huron on the west, to Toronto on the east,) we have then left 

 the greater part of Upper and the whole of Lower Canada. The 

 animals and plants of this peninsula appear to have decided affini- 

 ties with the western Natural-history province. Thus, in the 

 museum of the Natural History Society, the few fresh-water shells 

 from this region are well known western forms. As examples I 

 may cite : 



TJnio fragilis, Raf. Unio flavus, Raf. 



(= U. gracilis, Barnes.) j (= U. rubiginosus, Lea.) 



"• subrotundus, Raf. " quadrulus, Raf. 



(= U. circulus, Lea.) (= TJ. lacrymosus, Lea.) 



" costatus, Raf. Physa gyrina, Say. 

 (= U. undulatus, Barnes.) 



Judging from what we know of the zoology and botany of 



