SOG A MANUAL OF AMERICAN LAND SHELLS. 



1n<]r, iSubequally reflected, that of the columella narrow, adherent, or 

 subdilated and spreading. Greater diameter ]6i, lesser 14i'""; height, 

 10""". 



Helix MUcheUiana, Lea, Am. Phil. Trana., vi, 87, pi. xxiii, lig. 71 ; Obs., ii, 87 (1839); 

 Troschel, Arch. f. Nat., 1839, ii, 221.— De Kay, N. Y. Moll., 45 (1843).— 

 Pfeiffer, Mon. Hel. Viv., i, 291; iv, 322. — Blaxd, Ann. N. Y. Lye, vi, 339 

 (1858).— W. G. BiNXEY, Terr. Moll., iv, 47; L. A: Fr.-W. Sh., i, 141 (1869). 



Helix clausa, BiNNEY, Terr. Moll., ii, ll9; in iii, pi. iv, outliue figures. 



Mesoclon llitcIuJUaua, Try'OX, Am. Jonru. Conch., iii, 45 (1867).— W. G. Binney', 

 Terr. Moll., v, 323. 



Kentucky and Ohio, along the Ohio Eiver; Monroe County, Vir- 

 ginia ; Cherokee County, North Carolina. A species of the Interior 

 IJegion. 



Ill M. claust(s the umbilical region is more widely excavated, and 

 the groove behind the reflected peristome producing the contraction 

 of the aperture is coutiuued at the base of the shell, becoming wider 

 as it joins the umbilical opening. In M. MitchcUianns the groove is 

 almost obliterated at the point of reflection of the peristome over the 

 umbilicus by the more tumid character of the last whorl. 

 Jaw arcuate, of uniform width throughout; ends blunt; anterior 

 Fig ■ill surface with 12 crowded, coarse ribs, denticulating 

 either margin. 



Lingual membrane (Terr. Moll., V, Plate VIII, Fig. 

 Jnwot H) with 40-1-49 teeth; 18 laterals. Outer laterals have 



2i. Mitclicllianus. ... , . . 



Side cusps aim cutting points. 

 The genital system is long and narrow. The oviduct is greatly con- 

 voluted. The penis sac is long, stout, cylindrical, with a bulb-like 

 expansion at its apex, at which point both vas deferens and retractor 

 muscle are inserted. The genital bladder is lengthened, ovate, not 

 much larger than its duct, which is short, and enters the vagina below 

 the middle of its length (Terr. Moll., V, Plate XI, Fig. H). 



Mesodoii t'levatus. Say. 

 Shell imperforate, very convex, elevated, almost conical : epidermis 

 Fig. 32?. yellowish horn-color; whorls nearly 7, rounded, with 



fine, oblique, transverse striie, the last ventricose; su- 

 ture distinct ; a])erture contracted by the peristome, 

 somewhat triangular; peristome white, thickened, re- 

 flected, its basal portion with an obsolete, lamellar 

 M.cicratns. dcuticle ; parietal wall with a large, white, robust, ob- 



licjuely ciii'sed tooth : umbilicus covered. Greatei- diameter -.'), lesser 

 20- ; height, 7""". 



