HYALINA. 



401 



Fig 660. 



H. rxi^ua. 

 Enlarged. 



Surface of H. exigua. 

 Eularged. 



elevated, apex free from strice ; whorls 

 three and a half, convex, the last 

 rounded, widely lunbilicatcd below ; 

 aperture oblique, transversely round- 

 ed, remote from its axis ; peristome 

 simple, acute, its columellar extremity 

 not reflected. Greater diameter two 

 and a half, height one half, millimetres. 



Canada, New York, and New England ; also Tawas Bay, Michi- 

 gan. 



Hyalina milium. 



Shell depressed, transparent, shining; whorls three; aperture sub-circular; lip 

 simple ; widely umbilicated. 



Hdix milium, Morse, Proc. Bost. Soc. vii. 28 (1859). — W. G. Bixnet, Terr. Moll. iv. 



101, pi. 79, figs. 4, 5. — Morse, Amer. Xat. i. 54-3, fig. 36 (1867). 

 Striatum milium, Morse, Journ. Portl. Soc. i. 18, figs. 41, 42; pi. 7, fig. 43 (1864). 

 Pseudo-hyalina milium, Tryox, Am. Journ. Conch, ii. 265, pi. 4, fig. 56 (1866). 



Shell widely umbilicated, depressed, transparent, shining white, 

 with a greenish tinge, marked with distinct and regular 

 strise of growth and microscopic revolving lines, the lat- 

 ter more conspicuous below ; spire but slightly elevated ; 

 whorls three, rounded, rapidly increasing, the last plan- 

 ulate above, widely umbilicated below ; aperture very ob- 

 lique, sub-circular, remote from the axis ; peristome 

 simple, acute, its terminations somewhat approached, 

 that of the columella not reflected. Greater diameter 

 one and a half, height one half millimetres. 



The surface of the shell is raised in numerous folds, 

 frequently anastomosing; longitudinal ribs reticulate the surface 

 and render the folds so crenulated that in certain lights the shell 

 appears as if ornamented with strings of beads. This peculiar char- 

 acter disappears at the base of the shell, and is replaced by revolv- 

 ing lines and regular lines of accretion. 



Massachusetts and ]\Iaine. It is quoted doubtfully from Califor- 

 nia by Cooper. 



Fig. 662. 



Hyalina ferrea. 



Shell depressed-globose, transparent, not shining ; whorls three ; aperture large ; 

 peristome simple ; umbilicated. 



Striatwa ferrea, Morse, Proc. Portl. Soc. i. 17, figs. 36-40; also pi. 2, fig. 10 (1864). 

 26 



