Measurements 



1 Lip broken. 



Remarks The whereabouts of Dawson's original material of his Helix 

 limilaris, or even the certainty of its existence, is unknown. Although the 

 original description is very good it was unaccompanied by a figure, and 

 there has been much speculation as to the exact' systematic position of the 

 species. The writer had always supposed the type to be in the collection 

 of the Geological Survey at Ottawa but Mr. Johansen, who has been to 

 considerable trouble in the matter, states that he has been quite unable to 

 locate it there, and he met with only negative results in all attempts to 

 push the quest further. Information has been obtained that the type is 

 not in the British Museum, nor in the Redpath Museum of McGill Univer- 

 sity, nor in any of the other collections in Canada or the United States 

 where it has been thought worth while to make inquiry. 



The loss of the type material is not, however, so disastrous as it might 

 be, since the Survey possesses other specimens as herein described, collected 

 by J. B. Tyrrell of Toronto, who was assistant to Dr. Dawson on a sub- 

 sequent exploration of the same region, and who writes (in litt.} that they were 

 obtained from the same general locality and most probably from the ident- 

 ical swamp where Dawson collected the originals. 1 Likewise Mr. Johansen 

 has ascertained that there are five specimens of "Helix limitaris Dawson," 

 collected by the North American Boundary Commission, in the British 

 Museum. 



The accord of the present specimens with the original description is 

 reasonably complete throughout, and hence the writer's description given 

 above may be taken as merely amplifying that of Dawson. The number 

 of whorls, however, seems usually slightly more than he states (5|),sohis 

 specimens would not appear to have been entirely characteristic with re- 

 spect to this detail. 



1 "Dr. Dawson found very few specimens of this species near the shore of Waterton lake in 

 1874, when he was geologist on the British-North American Boundary Commission .... In 

 1883 I was acting as assistant to Dr. Dawson in his exploration of that portion of the Rocky moun- 

 tains lying between the Forty-ninth parallel and the Bow river. Dr. Dawson did most of the 

 geological work himself and my duties that year were largely topographical, but at the same 

 time I attended to the collection of plants and some small mollusks and Crustaceans. On the 

 evening of August 24 w r e all camped at the north end of the southern and larger of the two parts 

 of Waterton lake, and that evening I found near the shore some specimens of 'Physa 2ordi.' 



"The next morning, namely August 25, Dr. Dawson went westward with the pack animals 

 up the South Kootenay pass, while I went round a short way to a swampy piece of land where, 

 around rotten logs, I found several specimens of 'Helix limitaris,' these doubtless being the ones 

 which are now in the museum of the Geological Survey at Ottawa. I believe that I collected 

 these specimens on the same swamp on which Dr. Dawson had collected his specimens nine years 

 before." (J. B. Tyrrell, in ., Sept. 17, 1918.) 



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