416 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



Var. minor. Length, 15 mill. Found by Mr. Robert Kennicott near the 

 Red River of the North, and at Fort Resolution, Great Slave Lake. 



Animal of a uniform amber-color, judging from the specimens preserved in 

 spirits in the collection of the Smithsonian Institute.* 



This is the largest known American Succinea. 



Mr. Say describes S. ovalis as showing the interior apex from the base of the 

 shell ; in other respects his description does not apply to this shell. Its aper- 

 ture is nearer that of S. ovalis, Gould not Say, but the peristome is much more 

 flexuose, and the upper third of the shell becomes gradually attenuated, so as 

 to give a sharp pointed appearance, though the spire itself is short. The re- 

 volving lines are sometimes continuous over the whole body-whorl, but gener- 

 ally interrupted, or confined to the interstices of the incremental stria; or 

 wrinkles. It shares this peculiarity with S. concordialis, Gould, and S. lineata. 



Named in honor of Dr. F. V. Hayden, the discoverer of the species. 



Jaw without anterior ribs ; lingual membrane as usual (PI. XVI. Fig. R) ; 



teeth 35135. 



Succinea retusa, LEA. 



Shell ovate-oblong, very thin, pellucid, yellowish; spire short; whorls 3; 

 aperture below dilate and drawn back. Diameter .3, length .7 

 Fig. 295. i nca . Ohio, near Cincinnati. 



A single specimen only of this species has come into my posses- 

 sion. It differs so much from any of the described species in the 

 dilatation arid retraction of the inferior part of the aperture, that 

 I have not hesitated to consider it new. (Lea.) 



S. retusa. Succinea retusa, LEA, Trans. Am. Phil. Soc., V. 117, PI. XIX. Fig. 

 86 (1837); Obs., I. 229. DEKAY, N. Y. Moll., 55 (1843).- 

 PFEIFFER, Mon. Hel. Viv., II. 525. BINNEY, Terr. Moll., III. 65, 66. W. 

 G. BINNEY, Terr. Moll, IV. 37, PL LXXIX. Fig. 7 ; L. & Fr.-W. Sh., I. 256 

 (1869). TRYON, Am. Journ. Conch., II. 238 (1866). 

 Succinea campestris, ANTHONY, Ohio Cat., no descr., part (1843), No. 95. 



Interior Region, near Cincinnati. 



Mr. Lea's original description and figure are copied above. 



Jaw, lingual membrane, and genitalia not observed. 



Succinea Sillimani, BLAND. 



Shell oblong-ovate, thin, coarsely striate, shining, whitish (?) ; spire short^ 

 acute ; whorls 3, convex ; suture impressed ; aperture oblique, elongate-oval, 

 angular above, effuse at the base; columella slightly 

 arcuate, with a thread-like thickening above. Length 

 20, diameter 8 mill.; aperture 13 mill, long, 6 broad 

 in middle. 



Suctinea Sillimani, BLAND, Ann. N. Y. Lye., VIII. 167, 

 Fig. 13 (1865). TRYON, Am. Journ. Conch., II. 236 

 (1866). S. Sillimani. 



