LYMNIDA OF NORTH AMERICA. 251 
causes the aperture to be continuous; umbilical chink round, wide and 
deep, exhibiting one or more volutions; the base of the shell is roundly 
flattened. 
Length. - Breadth. Aperturelength. Breadth. 
8.50 3.50 3.50 2.00 mill. Type 
8.75 4.00 3.50 2.00 ~ i 
7.60 3.50 3.00 LOOK ine: o 
Types: The Chicago Academy of Sciences, four specimens, No. 
23157; cotypes, Philadelphia Academy of Sciences, No. 89172. 
Type LocaLity: Owasco Lake, New York. 
ANIMAL, JAW, RADULA and GENITALIA: Unknown. 
RANGE: New York state. A species of the Alleghanian division 
of the Transition life zone and of the Canadian region. 
RECORDS. 
New York: Cazenovia, Madison Co. (Henderson) ; Owasco Lake, Cayuga 
Co. (H. N. Lyon); Cazenovia, Madison Co., and Williamsville, Erie Co. 
(Walker). 
GEOLOGICAL Rance: Unknown. 
Ecotocy: Along the shore on debris, such as sticks, reeds, etc., 
or on stones and submerged vegetation. 
REMARKS: Owascoensis may be known by its clongated, narrow 
sfire, turreted, flat-sided whorls and large, round, open umbilical chink. 
The whorls appear. when viewed in outline, like boxes of diminishing 
size set one upon another. The shape of the aperture is also peculiar. 
Its nearest ally is parva, from which it may be distinguished by its 
flat-sided and shouldered whorls, its generally compressed outline and 
its more open, round and deep umbilical chink which exhibits the last 
volution. 
Galba dalli (Baker). Plate XXX, figures 13-18. 
Lymne@a parva BAKER, Nautilus, XIX, p. 52, 1905 (not of Lea). 
Lymnea dalli Baker, Bull. Ill. State Lab. N. H., VII, p. 104, 1906; Nautilus, 
XX, p. 125, 1907 (description) —Hanna, Nautilus, XXIII, p. 96, 1909. 
SHELL: Very small, thin, ovate-conic, turreted; color greenish 
or whitish horn; surface dull to shining, marked by heavy, crowded 
growth lines which are elevated into indistinct ridges in some speci- 
mens; nucleus very small, flatly rounded, light horn-colored, similar 
in form to that of Galba parva. Whorls 4%-5, rounded and distinctly 
shouldered; spire generally obtusely conic, turreted, a trifle longer 
than the aperture; sutures very deeply impressed; aperture elongate 
ovate or elliptical, continuous in many specimens; outer lip acute; 
inner lip forming a rather flat erect extension over the umbilical region, 
leaving a pronounced chink; the lower part of the aperture is some- 
what effusive; the columellar extension of the inner lip is sometimes 
