INVERTEBRATES. 379 



in size, last one forming about one-third the entire length, 

 rounded, but not much produced below ; suture well defined ; 

 aperture oval subrhombic, slightly effuse on the inner side 

 below ; outer lip thin and nearly straight; inner lip a little reflex- 

 ed. Surface ornamented by small, regular, straight, vertical 

 folds or costae, about equaling the spaces between, and number- 

 ing near thirty on the body whorl. Costae obsolete on the under 

 side of the last turn ; no lines of growth visible under a lens. 

 Length, 0.36 inch; breadth, 0.15 inch; apical angle nearly 

 regular, divergence about 28 °. 



This species resembles the last two in its general appearance, but differs in 

 having more numerous, smaller, and more closely arranged costae. Its whorls 

 are also more convex, and its suture deeper. It is more nearly allied to L. 

 scalaroidea (sp.) of Phillips, but differs from de Koninck's figures of that spe- 

 cies, in having perfectly straight, instead of flexuous, costse. The number of 

 its costae is also less than in L. scalaroidea, and its spiral angle is greater than 

 given by de Koninck in his description (22°), though less than represented in 

 his figures (about 32°). 



Locality and position : Macoupin county, 111. ; Coal Measures. 



LOXONEMA CERITHIFORMIS, M. and W. 



PI. 31, fig. 13 a, 13 6, 13 c. 



Loxonema cerithiformis, Meek and Worthen, Oct., 1860. Proceed. Acad. Nat. Sci., 

 Philad., p. 465. 



Shell rather under medium size, elongate-conical; spire ele- 

 vated, gradually tapering to an acute point; volutions eleven 

 to twelve, convex, and increasing gradually in size; last one 

 not much enlarged, somewhat abruptly rounded below the 

 middle. Suture deep. Aperture oval subrhombic, a little 

 longer than wide, apparently provided with a small notch 

 or angularity at the base of the columella; outer lip thin, 

 rather distinctly sigmoid in outline ; columella somewhat tor- 

 tuous. Surface nearly smooth, but showing under a lens very 

 fine, obscure lines of growth, which curve parallel to the mar- 



