346 PALEONTOLOGY OF OHIO. 



Genus MACROCHEILUS, Phillips, 1841. 



(Palgeoz. Foss., 103.) 



Macrocheilus Klipparti, Meek. 



Plate 20, figs. 6a, b, c. 

 Macrocheilus Klipparti, Meek (1872) ; Proceed. Acad. Nat. Sci., Philad., XXIV., 328. 



Shell attaining a large size, elongate-subfusiform, the length being 

 sometimes from two and a half to three times the breadth ; spire /pointed 

 at the apex, forming about half the entire length, with its lateral slopes 

 concave above and convex below; volutions six to eight or nine, the 

 upper five or six being very compactly coiled, and forming comparatively 

 but a small part of the entire shell, while those below suddenly increase 

 in size much more rapidly than the others, particularly in the direction 

 of the longer axis of the shell, and form most of its bulk, these larger 

 turns in large, adult examples sometimes assuming together a sub-cylin- 

 drical outline; last or body whorl comparatively long, cylindrical, or 

 more or less oval, and somewhat produced below ; suture moderately dis- 

 tinct, almost transverse between the smaller upper turns, but becoming 

 decidedly more oblique below ; aperture comparatively small and nar- 

 row, apparently sub-rhombic in form and effuse below ; inner lip much 

 thickened all the way up ; columella twisted, so as to form a single prom- 

 inent fold below the middle of the aperture. Surface nearly smooth, or 

 only showing very obscure lines of growth. Outer lip unknown. 



Length of one of the largest, most elongated specimens, 2.23 inches ; 

 breadth, 0.87 inch ; length of aperture, about 1 inch. 



This fine species most nearly resembles M. Newberryi of Stevens, but 

 may be readily distinguished by its form, the slopes of the upper part 

 of its spire being distinctly concave and the lower part convex in out- 

 line, instead of being evenly and moderately convex all the way down. 

 This peculiarity is- caused by the sudden enlargement of the middle and 

 lower volutions, and the greater obliquity of their spiral curve, while in 

 M. Newberryi the volutions increase in size regularly, and have the same 

 uniform, spiral curve from the apex throughout the whole length of the 

 spire. Young examples of the form under consideration are proportion- 

 ally shorter, the elongation being to a considerable extent produced by 

 the obliquity and prolongation of the last two volutions. These less 

 elongated, younger shells, however, will be distinguished from M. New- 

 berryi by the concave slopes of their spire, and the greater proportional 



