FAMILY HEMIPHYLLIDIA — ANCYLUS. 13 
ANCYLUS CALCARIUS. 
PLATE V. FIG.99. a. s.—(STATE COLLECTION ) 
Description. Shell conic, calcareous, opake. Apex not central, moderately prominent. 
Aperture oval, entire ; the curves on the longest sides dissimilar. In very minute specimens, 
the edges somewhat everted. 
Color. Epidermis rufous, extending beyond the edges of the aperture ; within, bluish 
white, darker towards the apex. 
Length, 0-3. Height, 0-12. 
The specimen which furnished the above description was one of the largest which I have 
seen. ‘They are more commonly of the dimensions of A. rivularis. I separate it from this 
latter, chiefly on account of its solid calcareous structure. I am indebted to Mr. I. Cozzens 
for the specimens from the Passaic river, near Patterson ; but it will doubtless be found in 
this State. 
ANCYLUS FUSCUS. 
A. fuscus. ~ Apams, Bost. Jour. Nat. Hist. Vol. 3, p. 329, pl. 3, fig. 17. 
A. id, Gov Lp, Invertebrata Mass. p. 224, fig. 152. 
Description. Shell rounded oval, the entire outline regularly curved, thin and pellucid, 
depressed ; convexity regular, not compressed at the sides. Apex obtuse, a little to the 
right of the centre. Epidermis coarse, strong and rough, extending beyond the margin of the 
shell. 
Color. Epidermis dusky yellowish brown ; within, glistening, polished. 
Length, 0°3. Height, 0°01. 
This species has been observed in Massachusetts, and will probably be found in this State. 
It appears to be a very distinctly marked species. 
(EXTRA-LIMITAL.) 
A. tardus. (Say, Des. terr. et fluv.) Shell conic, depressed. Apex behind the middle, obtuse, rounded, 
inclining backwards, but not laterally. Line from the apex to the posterior tip rectilinear ; line 
from the apex to the anterior tip arcuated. Aperture oval, not distinctly narrowed at one end. 
Length, 0°15; breadth, 0-1. Wabash River. Ly 
A, filosus. (Conrap, Fresh Water Shells, p. 57.) Shell regularly oval, rather elevated, with nu- 
merous radiating prominent lines. Apex very prominent, inclined, eroded, not nearly central. 
Abundant on Melania. Alabama. 
A, nuttallii, (Hap. Monog. Lymn. No. 3.) Shell oval, elevated. Apex one-fourth of the entire 
length from one end. Color fuscous. Length, 0+3; breadth, 0°25; height, 0°09. Oregon. 
A. diaphanus. (Hatp. Ib.) Shell regularly oval, very wide, depressed. Apex sub-central. Color, 
very pale, translucent. Length, 0°25. Ohio. 
A. parallelus. (Hatp, Adams, Am. Jour. Vol. 40, p. 275.) 
