50 ON THE LAND AND FRESH-WATER 



to evolve chlorine, and by the time this has ceased the second 

 furnace will have commenced to yield that gas, and the first 

 furnace might be charged with new materials. Thus a continu- 

 ous stream of chlorine and sulphurous acid would be kept up, and 

 on mixing these with steam, and condensing them as above des- 

 cribed, a mixture of sulphuric and muriatic acids would result, 

 which is to be treated as above indicated. 



Actonvale, Canada East. 16 February, 1863. 



Abt. V. — On the Land and Fresh-water Mollusca of Loiver 

 Canada ; by J. F. Whiteaves, F.G.S., &c. 



(Read before the Natural History Society.') 



Part I. — General Considerations. 



Various papers of interest have appeared in the Canadian 

 Naturalist, on the distribution of the land and fresh-water mol- 

 lusca in Lower Canada. "We are indebted to Messrs. Billings, Bell, 

 and D'Urban, for nearly all the information we possess on this 

 subject. Within the last two years new labourers have entered 

 the field, and the result has been some addition to our knowledge 

 of the geographical range of these creatures in Lower Canada. 



My friend, Mr. R. J. Fowler has collected assiduously and suc- 

 cessfully in the vicinity of Montreal, and in the Eastern Townships. 

 In the summer of 1861 I paid special attention to the inland mol- 

 lusca of the neighbourhood of Quebec, and collected in several 

 places in the St. Lawrence valley, from Riviere du Loup to Mont- 

 real. Last winter I endeavoured to call the attention of the mem- 

 bers of the Natural History Society to a short consideration of 

 this subject. On looking over this brief sketch (vide Canadian 

 Naturalist, vol. 6, page 452) I find two or three errors have crept 

 in, caused by my want of access to the proper authorities on the 

 subject in Quebec. In the present paper I hope to be able to rec- 

 tify these mistakes. I propose, partly from original enquiry, and 

 partly availing myself of the labours of others, to collect together 

 in one paper, all that we know of the geographical distribution of 

 the inland mollusca of Lower Canada, up to the present date. I 

 shall also indulge in some general speculations which the subject 

 "naturally suggests to my own mind. 



Let us first consider the most obvious geographical affinities of 



