STENOTREMA. 299 



descr. BINNEY, Bost. Journ. Nat. Hist., III. 363, PI. X. Fig. 2, not of 



WOOD. 

 Helix monodon, DEKAY, N. Y. Moll. 1. c., ex parte, PI. III. Fig. 21, a, b 



(1843). WOOD, Ind. Suppl., PL VII. Fig. 15. 

 Helix convexa, CHEMNITZ, ed. 2, I. 86, ex parte. Var. REEVE, Con. Icon. 1. c. 



/3, PFEIFFER, Mon. Hel. Viv., I. 420. 

 Helix monodon, /3, PFEIFFEK, 1. c., IV. 320. 



VAR. LEAH. 



Helix convexa, y, PFEIFFER, 1. c. Var. CHEMNITZ, I.e., PI. LXVI. Figs. 24, 25. 

 Helix monodon, y, PFEIFFER, IV. 320. Part BINNEY, Terr. Moll., PL XLI. 



central figures. 

 Helix Leaii, WARD, MS. teste BINNEY. 



- LISTER, Syn. Conch., PL XCIII. Fig. 94. 



In the post-Pleioeene of the Mississippi Valley ; now found in Canada and 

 all the Eastern Province to Texas. 



Animal yellowish-brown, darker on the head, neck, eye-peduncles, and ten- 

 tacles. Foot narrow, cylindrical, one and a half times as long as the diameter 

 of the shell, terminating in a point. Eye-peduncles one fourth of an inch long. 

 Eyes black. Some individuals much darker than others (see B. J. N. II., I. 

 PL X). 



The varieties of this shell present remarkable differences in size and color- 

 ing, and in the form of the umbilicus. The transverse diameter varies from 

 one sixth to three sixths of an inch, and the form from subglobular in small 

 specimens to a very flattened shape in the larger. The coloring exhibits every 

 shade, from light amber to dark chestnut, sometimes with a revolving band, 

 and then known as var. cincta. 1 The whorls of some revolve about the axis at 

 such a distance as to leave a deep and wide umbilicus (monodon) ; while in 

 others they are in such near approximation as to permit only a small perfora- 

 tion, which the narrow, reflected peristome is sufliciently wide to cover (fra- 

 ternum). The hairy projections of the epidermis are most distinct upon the 

 young shells, but are often wanting at every stage of growth. The oblique 

 stria? are so fine as hardly to be visible, and in some instances the shell ap- 

 pears to be glabrous. Very beautiful specimens, about one fourth of an inch 

 in diameter, with a dark, shining epidermis and open umbilicus, occur in Ohio, 

 Indiana, Iowa, and Michigan. They are more convex, and as the same num- 

 ber of volutions is contained in half the space, they appear to have more whorls 

 than the common variety. Some persons have considered these to form a dis- 

 tinct species (H. Leaii, Ward, MS.) ; but I do not see that they can, with 

 propriety, be separated. 



In the Western States this species is generally found in the forests. In 

 New Hampshire and Vermont it is also found in forests with other species, but 



* Hayes ville, North Carolina. See Lewis, Proc. Phila. A. N. S., 1874, p. 162. 



