North American Helicidce. 31 



■which is probably retained and collected by the hairs. When unen- 

 cumbered by this vesture, the shell is of a horn color. It is by no 

 means so common as the preceding species (P. auriculata)." 



No specimen of this comparatively rare shell is now to be 

 found in the cabinet of the Academy at Philadelphia. 



In the above synonymy I exclude all mention of the writings 

 of Dr. Binney, in the confident belief that he entirely misinter- 

 preted this species. In the Boston Journal he refers to PI. xix. 

 fig. 1, as the mature 11. auriculata^ and to fig. 2 " as the yonng 

 shell described by Say as P. avara^'' His remarks are repeated 

 in the Terr. Moll., with an additional observation as to the size 

 of the shells. From the latter work I quote the follovving : — 



"At different periods of growth the aperture differs very much in 

 appearance, and has led naturalists into error. When the lip is just 

 beginning to be formed, and as yet projects but little, there are two 

 projecting teeth on its inner edge, with a deep sulcus between them ; as 

 these continue to grow, they assume more and more the appearance of 

 lamebar folds, the lower one of which, when viewed on a line perpen- 

 dicular to the base of the shell, hides the other. The colnmellar fold, 

 at the same early period, appears more like an independent tooth, to 

 each extremity of which the lip is connected. It is this variety which 

 Mr. Say described as a distinct species, under the name of Polygyra 

 avara. This opinion I derive, not so much from his descriptions as 

 from the examination of original specimens collected and labelled by 

 him, now in my possession. I have specimens of the mature shell 

 smaller than any specimen of H. avara that I have seen, and have other 

 specimens of H. avara, so called, as large as the most mature H. auri- 

 culata. Plate XL. fig. 1, represents the mature shell, fig. 2, the young 

 shell, described by Say as P. avara.''' 



The whole tenor of the above remarks is certainly erroneous. 

 "With respect to the shells " collected and labelled " by Say, it 

 is possible that he, at a period subsequent to the publication 

 of his diagnosis, may have distributed as II. avara specimens 



