STENOTREMA. 291 



shorter, the cutting points more produced, and thus gradually the form of the 

 marginal teeth is reached. They are low, wide, the reflection equalling the 

 base of attachment, the cutting points long, oblique, usually two in number, 

 the inner one generally, and the outer one rarely, bluntly bifid : the outer 

 bifurcation of each is more produced than the inner. There is great varia- 

 tion in the denticulation of the marginal teeth even on the same lingual mem- 

 brane. A transition from laterals to marginals similar to that of S. spinosum is 

 found in S. barblgerum, labrosum, Edvardsi, stenotremum, Mrsutum, gerrnanttm, 

 and monodon. 



There seems no difference in the characters of the teeth of the different 

 species examined by me, excepting the slight one of the greater or lesser devel- 

 opment of the side cusps of centrals or laterals, especially the former; whether 

 this is constant can only be proved by a careful examination of every portion 

 of each lingual. In S. hirsutum I found these cusps more developed than in 

 the other species. 



Stenotrema spinosum, LEA. 

 Vol. III. PI. XLIV. Fig. 1. 



Shell imperforate, lenticular, with the upper surface much flattened, acutely 

 carinated; epidermis dark chestnut-color, with minute, hair-like processes lying 

 flat upon the whorls in the direction of their lines of growth, 

 striate ; whorls 6, of nearly uniform width, and decreasing very Fi S- 189. 

 gradually from the aperture to the spire ; suture distinct, slightly 

 raised ; aperture very narrow ; peristome yellowish-white, near 

 its junction with the body-whorl thickened, angulated, and slightly 



reflected, with a median cleft ; parietal wall with a long, yel- 



' S. sfinosum. 



lowish, narrow, projecting tooth, extending from the umbilical 

 axis to the angle of the peristome, and parallel with its thickened edge ; base 

 convex, with the umbilical region slightly indented; within the shell, springing 

 from the axis, is a transverse, curved, white tubercle. Greatest diameter 14, 

 lesser 13 mill. ; height, 6 mill. 



Caracolla spinosa, LEA, Am. Phil. Trans., IV. 104, PL XV. Fig. 35 ; Obs., I. 114 

 (1834). 



Helix spinosa, BINNEY, Bost. Journ. Nat. Hist., III. 367, PI. XL Fig. 2 (1840) ; 

 Terr. Moll., II. 153, PI. XLIV. Fig. 1, excl. syn. PFEIFFER, Mon. Hel. 

 Viv., I. 421 ; in CHEMNITZ, ed. 2, I. 375, PI. LXV. Figs. 15-17 (1849). DE- 

 KAY, N. Y. Moll., 47, PI. V. Fig. 114 (1843). REEVE, Con. Icon., 685 

 (1852). W. G. BINNEY, Terr. Moll., IV. 65 ; L. & Fr.-W. Sh., I. 113, Figs. 

 189, 190 (1869). 



Stenotrema spinosa, TRYON, Am. Journ. Conch., III. 58 (1867). 



A species of the Cumberland Subregion, common in East Tennessee, ranging 

 into Alabama and Georgia. 



