398 HELICID^. 



nearly a direct section of the whorl in this. Though all of the same 

 size and general appearance, the three may be readily separated, 

 when seen in company. Indeed, its claims as a distinct species are 

 not very obvious without viewing the three together. It may be 

 briefly described by saying that it resembles H. indentata above, 

 and H. arbor ea beneath. 



This shell was first discovered by Mr. T. J. Whittemore, about 

 the borders of Fresh Pond, in Caml)ridge, where it has since been 

 found abundantly by him and by myself, under fragments of board 

 in damp places, near the water's edge, in company with H. chcrsina 

 and Pupa modesta. I have never seen it in company with either 

 H. indodata or H. arborea; and it seems to differ widely from them 

 in its habits, in thus preferring the vicinity, and even the intrusion, 

 of water. Professor Adams informs me that he has selected numer- 

 ous specimens of this species from among small snails collected by 

 him in Missouri. 



It occurs from Great Slave Lake to the Gulf of Mexico. Also in 

 Europe, as is now generally believed, having been referred to H. 

 viridula, Menke. 



Hyalina indentata. 



Fig. 109. 



Shell orbicular, depressed, very thin and shining; whorls four, the external one 

 marked with rather distant impressed lines radiating frona the closed umbilicus; 

 lip simple. 



Helix indentata, Say, Joiu'ii. Acad. ii. 372 (1822) ; Binnet's cd. 24. — Binney, Best. 

 Journ. Nat. Hist. iii. 415, pi. 22, fig. 3 (1840) ; Terr. Moll. ii. 242 ; pi. 29, fig. 2. — 

 De Kay, N. Y. Moll. 31, pi. 3, fig. 26 (1843). — Gould, Inv. 181, fig. 109 (1841). 



— Adams, Vermont Moll. 160 (1842). — Chemnitz, 2d ed. i. 21, pi. 34, figs. 12-15. 



— Pfeiffer, Mon. Hel. Viv. i. 59. — Reeve, Con. Icon. 730 (1852). — W. G Bin- 

 ney, Terr. Moll. iv. 119. — Morse, Amer. Nat. i. 413, fig. 28 (1867). 



Hyalina imkntata, Morse, Journ. Portl. Soc. i. 12, fig. 21 ; pi. 2, fig. 11 ; pi. 5, fig. 22 

 (1864). — Tryon, Am. Journ. Conch, ii. 246, pi. 3, fig. 11 (1866). 



^I^^"- Shell small, orbicular, very low conical, thin, pellucid, 



very light horn color, highly polished and shining ; whorls 

 four, slightly convex, the whole spire having a conical 

 slope from the apex to the edge ; the outer one rapidly 

 increasing, marked with somewhat remote, sub-equidistant 

 impressed lines, in the direction of the lines of growth, 

 the intervening spaces very smooth ; suture moderately 

 deep ; aperture large, well-rounded ; lip simple ; base having the 



