EASTERN PROVINCE INTERIOR REGION SPECIES. 319 



loDg-, receiving- tbe retractor muscle at about the middle of its length, 

 and tai)ering very gradually towards its summit into tbe vas deferens; 

 genital bladder large, globose-oval, on a long, narrow duct. The penis 

 sac is very different from that of 21. Sayii. 



Mesodoii Sayii, Binney.* 



Shell umbilicated, orbicularly depressed, thin; epidermis light russet, 

 shining ; whorls between 5 and G, with numerous fine, fig. 3J3. 



oblique stride; suture impressed; aperture Innately 

 subcircular, not dilated; peristome white, narrow, 

 thickened, reflected, with a slightly projecting tooth 

 on the inner edge of the basal portion near the um- M.sayu. 



bilicus; parietal wall Avith a subprominent, white tooth; umbi icus 

 open, deep, not wide, exhibiting all the volutions, slightly contracted 

 by the reflected peristome; base rounded, with the stria? distinct, con- 

 verging into the umbilicus. Greater diameter 27,t lesser 23"""; height, 

 17'"'". 



Helix diodonta, Say, Long's Exped., ii, 257, pi. xv, tig, 4 (1824); ed. Bixney, 39, pi. 



Ixxiv, tig. 4.— De Kay, N. Y. Moll., 34, pi. ii, fig. 18.— Desha yes, iu F]6k., pi. 



Ixix, 1, fig. 2. 

 Helix Sai/i, Binney, Bost. Jonrn. Nat. Hist., ill, 379, pi. xvi (1840); Terr. Moll., ii, 



180, pi. xxiii.— Adams, Vermont Mollusca, 160 (1842).— W.G. Binney, Terr. 



Moll., iv, 70; L. & Fr.-W. Sli., i, 153 (1869).— Pfeiffeh, Mon. Hel. Viv., i, 



382 ; in CuEMNrrz, ed 2, iii, 419, tab. cxlviii, figs. 13, 14.— Leidy, T. M. U. S., 



i, 256, pi. xi, figs. 1-4 (1851), anat.— Mks. Gray, Fig. Moll. An., pi. cxeiii, fig. 



10, from Bost. Journ., no descr. — Deshayes, in Vi:R., i, 79. — Reeve, Cim. 



Icon., No. 679 (1852).— Mouse, Anier. Nat., i, 9^, figs. 4, 5 (186T).— Gould and 



BiNNEY, Inv. of Mass., ed.2,426 (1870).— Lewis, Am. Journ. Conch., vi, 191, 



pi. xiii, figs. 5-7 (1871). 

 Mcsodon Saijii, Morse, Journ. Portl. Soc, i, 9, fig. 9, pi. iv, fig. 10 (1864). 

 Ulostoma Saiiii, Tryon, Am. Jonrn. Conch., iii, 38 (1867). 

 Mesodon Sayii, W. G. Binnky, Terr. Moll., v, 339. 



Northern and Interior Eegions, from Canada East to Michigan, 

 ]\Iaryland, Kentucky, and Tennessee ; in the last locality greatly de- 

 veloped, a specimen figured by Lewis (/. c.) measuring 1.40 inches. 



Animal light reddish-brown, eye-peduncles and tentacles smoj^y, 

 eyes black; head and neck cylindrical, foot narrow, terminating in an 

 acute point; length about twice the diameter of the shell. (See Bost. 

 Journ. Nat. Hist., I, Plate XVI.) 



On the 3d day of July, 1830, Dr. Binney discovered an individual 



*The name diodonta, which has not i)recedence iu the genus Helix, may be adopted 

 in Mcwdou by those who follow the strict laws of nomenclature ; I doubt myself the 

 ]ii'opriety of changing the long-established name in any of the genera formed from 

 disintegrated Helix, and such is the rule now adopted by universal consent of authors. 



t One spccimou measured 41"'". 



