304 A MANUAL OF AMERICAN LAND bHEILS. 



suuiller, short, swollen at its entrance iuto the vagina; oviduct greatly 

 couvoluted. 



Mcsofloii Peiiiisylvaiiiciis, Gueen. 



Shell imperforate, convex, elevated ; epidermis yellowish horn-color or 

 russet; whorls 6, convex, with crowded, elevated, oblique 



FUi. 324. 7 7 7 7 7 1 



strice ; suture distinctly miirked ; aperture subtriangular, 

 contracted by the peristome; peristome white, narrow, 

 reflected, not flattened, with sometimes a slight thicken- 

 '^ -_ iug on the inner side near the base; umbilical region in- 

 M.rennsyivanicus. dentcd. Greater diameter 17, lesser 15"""; height, 11""". 



Hcl'tx rennsylvanwa, Greex, Contributions to M.'icl.Lyc, Nos. 1, 8.— Binney, Bost, 

 Jonrn. Nat. Hist., i, 483, pi. xvi (1837) ; Terr. Moll., ii, 105, pi. vii.— Pfeikfer, 

 Symbohe, ii, 36; Mon. llel. Viv. , i, 291 (oxcl. II . dausa) ; iv, 321 ; in Chem- 

 nitz, ed. 2, ii, 51, t. Ixxiii, figs. 4, 5 (excl. B. claiisa).—I)v:. Kay, N. Y. ]\Io11., 

 41, pi. iii, fig. 35 (1843).— Mrs. Gray, fig. Moll. Au., pi. ccxci, lig. 5, from 

 Bost. Jonrn, no descr.— Keeve, Con. Icon., No. 676 (excl. syn.). — Blaxd, 

 Ann. N. Y. Lye, vi, 299 (1858).— W. G. Binney, TejTr.Moll., iv, 15; L. & Fr.- 

 W. Sh., i, 140 (1869). 



Helix Mitchclliatra, Desiiayes, in Vi:R., i, 137, pl.xcvii, figs. 4-7, not 13-16. 



Mesodon Pcnnsijlvnnica, Tryon, Am. Jonrn. Conch., iii, 44 (1867).— W. G. Binney, 

 Terr. Moll., v, 321. 



Western part of Pennsylvania; Ohio; Illinois; Kentucky; Monroe 

 County, Virginia. It thus appears a species of the Interior Eegion. 



Animal : Upper surface of a dull, uniform leadcolor, lower surface 

 of the foot lighter ; about twice as long as the transverse diameter of 

 the shell (see B. J. K H., I, Plate V). 



This species may be readily distinguished from clausus and MitcheUi- 

 anus by its somewhat triangular aperture, which is more like that of 

 elevatus ; it is more elevated, has usually G whorls, more convex, and 

 with deeper suture than in clmisus. In mature shells the inner margin 

 of the peristome, near the columelki, has a tooth-like callus, very simi- 

 lar to that often prevailing in forms of exoletus, ihyroides, and albohihris. 

 The umbilicus is invariably more or less open in clansus, but closed in 

 Pennsylvanicus and MitclidJianus. 



Green described this species in 1827, and deposited three specimens 

 of it in the collection of the Philadelphia Academy, where they are 

 still preserved. In 1837 another description and an excellent figure 

 were published by Dr. Biuney in a well-known and widely circulating 

 journal. It is therefore surprising that so many authors and collect- 

 ors have confounded it with Ji. clausus, quite a distinct species. 

 Such, however, has been the case, as a reference to the above syii' 



