34 



LAND AND FRESH- WATER SHELLS OF N. A. [PART I 



same character as the other species of the subgenus described 

 above ; the two inner laterals with a small lateral denticle. 



Fig. 41. 



Hyalina viridula, Menke. — Shell umbilicated, small, depressed, 

 thin, fragile ; epidermis pale, or brownish horn-color, wrinkled, shining ; 

 whirls four, the last rapidly enlarging towards the aperture ; 

 aperture transversely rounded ; peristome simple, its edge 

 rather thickened, not acute ; umbilicus small, but well marked 

 and constant. Greater diam. 5, lesser 4§ ; height 2 mill. 



Helix electrina, Gould, Invert. 183, f. Ill (1841).— Bixney, 

 Uost. Journ. Nat. Hist. Ill, 423, pi. xxii, f. 2 (1840) ; 

 T. M. II, 286, pi. xxix, f. 1.— DeKay, N. Y. Moll. 30 

 (1843).— Adams, Vermont Mollusca, 161 (1842).— W. 

 G. Bixney, Terr. Moll. IV, 107.— Morse, Amer. Nat. I, 

 542, f. 31 (1SG7). 

 Helix pura, Aldek, teste Pfeiffer, Mon. Hel. IV, 83. 

 Helix janus, Adams MS. (olim). Shells Vt. Am. J. Sc. [i], XL, 273 (1841). 

 Zonites radiatuhis, Reeve, Br. Land and Fr.-W. Sh. 50, fig. (1SG3). 

 Zonites striatula, Moqcin-Tandon, Moll. Fr. teste Reeve. 

 Helix viridula, Menke, Syn. Meth. ed. 2, 127 ; see also Mai. Blatt. VIII, 92. 

 Hyalina electrina, Morse, Journ. Portl. Soc. I, 13, f. 23, pi. vi, f. 24 

 (1864).— Tkyon, Am. Journ. Conch. II, 251, pi. iv, f. 25 (18G6). 



From Great Slave Lake to the Gulf of Mexico. 



Europe. 

 Fig. 42. 



Also in 



Jaw arcuate, ends at- 

 tenuated, pointed ; ante- 

 rior surface centrally some- 

 what striate ; concave 

 margin smooth, Avith a 

 median rounded projec- 

 tion, on each side of which 

 are two notches. 



Lingual membrane with 54 rows of 27 — 1 — 27 teeth, arranged 



Jaw of Hyalina viridula. [Morse.] 



