Hemarhs on Certain Sjpecies of N. A. Helicidw. 131 



and aperture can be fully seen, agrees entirely with Say's de- 

 scription o^ H. lucuhrata, so nnicli so as to favor the conchision 

 that it is an authentic example, if not indeed his type. It is 

 appropriately compared with H. laevigata Raf. {inornata Say\ 

 but as Say remarks, the umbilicus is " much larger," nearly 

 equal to that of Il.fuliginosa, and the aperture " more accu- 

 rately rounded," being somewhat wider, but much like that 

 of Griffith's species. The shell is in color darker above than 

 usual in H. Icmigata^ the darker shade extending over the 

 periphery and terminating abruptly, where the paler color of 

 the base prevails. The margin of the last whorl, at the suture, 

 has indications of a line of a deeper reddish brown color than 

 that of the rest of the upper surface of the shell. 



The incremental stride are well defined " wrinkles," but of 

 irregular elevation, and not equidistant. The shell has five 

 whorls, less rapidly increasing than mil. Imvigata, and the follow- 

 ing are its dimensions : — 



Diam. maj. 26, min. 23, Alt. 11^ milk Ap. 12 mill long. 12 lat. 



This Academy specimen differs from examples of H. caduca 

 Pf. received from Mr. Cuming and M. Salle in the following 

 particulars ; it is more strongly " wrinkled," of darker color 

 above, and the aperture is more orbicular — the last whorl is 

 more ventricose. 



A specimen of H. caduca in my cabinet, with 5^ whorls? 

 measures, Diam. maj. 26, min. 2H, Alt. 10 mill. Ap. 10 mill, 

 long. 13 lat. The color is scarcely paler at the base than' above, 

 the umbilicus is the same as in the Academy shell, and the 

 whorls increase in the same proportion. Several young shells 

 have the same but more plainly discernible dark sutural line. 



Considering the Philadelphia specimen to be the II. lucuhrata 

 Say, I cannot pronounce it to be identical with H. caduca, but 

 intermediate between it and H. laevigata — more closely allied to 

 the former, and possibly a variety of it, certainly distinct from 

 the latter and from H. fuliginosa, and H. friahilis. 



