350 

 REPORT OF THE CONCHOLOGICAL BRANCH. 



To the Council of the Otlawo Field Naturalists Club : 



In presenting the report of the Conchological Branch, we have to 

 say, with regret, that but little woik has been clone in this department 

 during the past year. The absence from Ottawa, during the greater 

 part of the summer, of one of tlie leaders of this branch, and the busi- 

 ness engagements of the other, may lead you to regard with indulgence 

 our seeming neglect of duty. We have not, however, been altogether 

 remiss in fulfilling our obligations. To act in concert with other mem- 

 bers of the Club was, in many cases, impracticable ; but whenever the 

 occasion presented itself for individual work, it was eagerly made use of. 

 On the 17th iVJay, near the High Rock Apatite Mines, on the 

 River Libvre, a variety of the common white lipped snail, Jfesodon alba- 

 lahris var. dentata, was found which is of considerable interest, as throw- 

 ing light on an anomolous and hitherto unsatisfactorily explained i-ecoi'd 

 of " Helix exoleta Binney," from the valley of the neighboring river, 

 the Rouge (D'Urban, Can. Nat. & Geol., 1860, p. 81). In a paper 

 I'ead before the club on the 7th February, 1885, this record was doubted, 

 and it was suggested, as the only explanation which seemed possible, 

 that D'Urban's shell was really M. Dentiferus. Quite recently it was 

 noticed by one of the leaders of this branch that Mr. Whiteaves had 

 expressed the same doubt and made the same suggestion in the Canadian 

 yaturalist for 1863. No toothed mesodons but sayii and dentiferus 

 were known to occur in eastern Canada ; and as J/, sayii was enumer- 

 ated in the list of shells collected in the Rouge valley, M, dentiferus 

 seemed the only shell which could have been taken for J/, exoletus. 

 There remained, however, the difficulty of explaining how Mr. Binney, 

 who identified D'Urban's shells, could confound species which differ so 

 widely as M. exoletus and 3f. dentiferus. But the dentate variety of 

 J/, alholabris might I'eadily be taken for M. exoletus. The occurrence 

 of this well Tiiarked vaiiety at the High Rock Mines thus clears up a 

 doubtful though, perhaps, not very important, point in Canadian 

 Natural History. 



It is of interest from another point of view, as it extends the range 

 of the var. dentata very materially. It occurs in Alichigan, from which 



