32 



specimens of this species, excepting that the labi-nra is somewhat 

 more transverse. 



Pupa modesta. — Shell dextral, suboval, minutely wrinMed ; 

 apex obtuse ; whorls six ; umbilicus distinct ; aperture obliquely 

 subovate ; labium with a prominent, compressed, seraioval tooth, 

 equidistant from the extremities of the labrum, and a somewhat 

 conic one rather below the middle of the columella ; labrum 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 whorl 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 ovalis 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. 



