32 
specimens of this species, excepting that the labium is somewhat 
more transverse. 
Pupa modesta. — Shell dextral, suboval, minutely wrinkled ; 
apex obtuse ; whorls six ] umbilicus distinct j aperture obliquely 
subovate; labium with a prominent, compressed, semioval tooth, 
equidistant from the extremities of the labruro, and a somewhat 
conic one rather below the middle of the columella ; labrura not 
reflected, joining the preceding whorl at its upper extremity with 
a curve; bidentate, lower tooth placed opposite to that of the 
middle of the labium, the others smaller and placed a little 
above. 
Length less than one-tenth of an inch. Inhabits the North- 
west Territory. PI. 15, fig. 5. 
Var. a. — The smaller tooth of the labrum obsolete or wanting. 
SucciNEA AVARA. — Shell suboval, pale reddish-yellow, subdia- 
phanous, fragile, covered with an earthy crust ; whorls three, 
minutely wrinkled ; body wLorl very large ; spire small ; aperture 
large, subovate, about two-thirds of the whole length of the shell. 
Length three-twentieths of an inch. Inhabits the North-west 
Territory. 
This small species of Succinea occurs in humid places, very 
frequently under stones and near the water. The shell is always 
completely encrusted with a coating of earth. It may at once be 
distinguished from either the ovalis or campestris by its very small 
size. PI. 15, fig. 6. 
S. OBLIQUA. — Shell oblong-oval, nearly pellucid, pale amber- 
colored ; whorls three, very obliquely revolving, distinctly wrinkled ; 
spire a little prominent ; aperture suboval, somewhat oblique. 
Length seven-tenths of an inch ; length of the aperture less 
than one-half inch. Inhabits Pennsylvania. 
Of this fine species, found in the vicinity of Philadelphia, many 
specimens were some time since presented to the Academy Nat. 
Sc. by Messrs. Hyde and Mason, and we obtained a specimen near 
the Falls of Niagara. It may at once be distinguished from 
either the avails or campestris by the much greater obliquity of 
the revolutions of its whorls. It is very much like the helix 
putris of Linn., but it is more than double the size of that species. 
It may, however, be a variety of that shell. PI. 15, fig. 7. 
