212 AMERICAN JOURNAL 



tooth " — if applied to any North American species, would not ap- 

 ply to M. ? profunda, Say, which has such a tooth or tubercle, 

 because, as Mr. Tryon points out in this Journ. IV, p. 175, 

 Mesodon could not have an umbilicus, for " Odomphium differs 

 in having an ombilic." His type, 31. maculatum, judging from 

 the name, was spotted, variegated, or by a stretch of the term, 

 striped, and the only species having stripes and no umbilicus 

 found "in Kentucky " is multilineata, Say, which may then be 

 adopted as the type of the genus. 



But he had previously made a genus Odotropis (toothed whorl) 

 which had " lip reflected, umbilicus covered, tooth upon colu- 

 mella," (meaning paries, as is evident from his description of 

 Triodopsis). Although without a type mentioned, it is plain 

 that this could apply only to the exoleta group among Kentucky 

 species. 



I adopted the name as including H. ? devia, at first as a 

 section of 3Iesodon, Auct., to include those with a parietal tooth 

 and a tooth or tubercle on the lower lip also, near the true colu- 

 mella, being satisfied, like Morch, that these teeth were chiefly 

 specific or subgeneric characters only. I am now pretty well 

 satisfied that it ought to take precedence of 3Iesodon as a gene- 

 ric name, having twelve years priority; and should of course 

 include many toothless or umbilicate Eastern species, for which, 

 however, 3Iesodoti, Odomphium, and perhaps Trophodon, of same 

 date, may become subgenera. 



I was wrong, however, in adopting "umbilicus covered " as a 

 character of devia, though my specimen had it so ; for the spe- 

 cies is usually umbilicate, showing the uncertainty of this 

 character even as a specific mark. 



I did not include Totvnsendiana in the same genus in the 

 Geog. Catalogue, because it shows in the shell much afiinity to 

 Arionta, through arrosa, anachoreta, etc., and has even been put 

 unhesitatingly in that genus by Europeans, though difiering so 

 much from A. arbustorum. I now incline to think that it should 

 be put in Odotropis, and that the surface characters linking it 

 with the more southern Ariontas are merely similative, just as 

 we find the latter simulating or approaching Polymita as they 

 come from nearer its region of habitat. 



0. ? anachoreta, W. G. Binn. This can scarcely be the band- 

 less variety of arrosa, as suspected by Tryon, for it has one 

 whorl less (6), and specimens of arrosa quite as small have 7 ; 

 the lip also seems broader in proportion, like that of Dr. New- 

 comb's var. c of Nickliniana from Klamath Co., " without band, 

 umbilicus closed, not malleated ; lip broadly expanded." This 



