GASTEROPODA. 
43 
of the volution. On well preserved specimens the striae are sharply 
elevated, but are subject to considerable variation which may be due to 
erosion or maceration before imbedding. 
A critical comparison of specimens originally referred to this species has 
led to the conclusion that some of them should be separated, and the specific 
term restricted in its application to such forms as are here illustrated. 
Formation and localities. In limestone of the Upper Helderberg group, near 
Columbus, Ohio, and in some doubtful specimens from Genesee and Erie 
counties, N. Y. 
Loxonema pexata var. obsoleta. 
PLATE XIII, FIG. 13. 
Loxonema pexata var. obsoleta. Hall. Illustrations of Devonian Fossils: Gasteropoda, pi. 13. 1876. 
The specimen figured retains a part of three volutions—the last nearly entire. 
The form is the same as in typical specimens of L. pexata. The surface is 
marked by obscure or obsolete striae, which condition may be due to age or to 
maceration and erosion before imbedding. 
Formation and localities. In limestone of the Upper Helderberg group, at 
quarries north of Columbus, Ohio. 
Loxonema sicula n. sp. 
PLATE XXVI, FIG. 1. 
Shell small, slender, very gradually enlarging from the apex. Volutions short 
and moderately convex; fourteen in an entire specimen of seven-eighths 
of an inch in length; a narrow, flattened space at the upper margin of 
each one, which is limited below by an undefined line parallel to the suture. 
Surface marked by comparatively strong and coarse elevated strife, which 
curve gently backward from the suture to the middle, and thence forward 
to the base of the volution. 
Formation and locality. In decomposing chert of the Upper Helderberg lime¬ 
stone, near Jamesville, Onondaga county, N. Y. 
