PALEONTOLOGY. 4B3 



erable doubt on their identity, as the lower valve of this species is at- 

 tached over its entire surface, while that one would appear to be free or 

 partially free, if it is a Crania. 



Formation and Locality .—In the Coal Measures of Carbon Hill, 

 Hocking county, Ohio. Collected by' H. Moore's, Esq., of Columbus, 

 Ohio. 



MOLXUSCA. 



GASTEROPODA. 



Genus MACROCHEILUS Phillips. 



Macrocheilus regularis. 



Plate XI, fig. 13. 



Loxonema regularis Cox, Geol. Rept. Ky., vol. iii, p. 566, pi. 8, fig. 2, 1857. 



Shell of moderate size, fusiform, with an elevated, rapidly ascending spire 

 which is composed of about nine volutions, and has an apical angle of from twenty 

 to twenty-five degrees, in different individuals when not compressed. Spire, when 

 viewed iu front, forming considerable more than half the length of the shell, but 

 when measured on the opposite side forms a little less than one-half the entire 

 length. Volutions slightly convex and in some individuals presenting a slightly 

 shou'dered aspect caused by a very slight, almost imperceptible angularity at about 

 the upper third of the exposed part. Greatest diameter of the body-whorl situated 

 a little below the suture and decreasing below. Suture close and not strongly 

 marked. Aperture narrow, elongated, the outer lip sharp and compressed in the 

 upper part. Columella twisted and marked in the lower part by a single, but very 

 strong twisted fold ; anterior end of the lip rimate. Surface of the shell marked 

 only by obscure lines of growth. 



The species is one of the most elongated forms of the genus yet 

 recognized from the American Coal Measure strata, and will be readily 

 recognized by the great' length of the spine, especially as seen in a front 

 view; while the unusually strong columellar fold will also distinguish it. 

 In most of the specimens observed the body volution appears to con- 

 tract more abruptly above in its outer half than before, giving a some- 

 what unsymmetiical feature to this part of the shell. All the examples 

 seen are compressed in the direction of bedding, usually to the extent of 

 one-third of their original diameter or more, and some of them are en- 

 tirely flattened. This gives them in appearance a much greater apical 

 angle than the living shell really possessed, which may easily mislead 

 one in making a hasty comparison. The^ longest individual observed 

 measures two inches and five-eighths in length, and has a diameter of the 

 body-whorl of one inch. The shell is considerably flattened except in 

 the upper part of the spire, which shows the diameter of the lower part 

 to have been increased fully one-third. The species was originally de- 

 scribed by Prof. T. C. Cox, loc. cit, as a Loxonema, and his figure would 

 indicate a shell like Polyphemopsis, but feeling uncertain of its accuracy 

 in consequence of the great similarity, I procured the loan of the type 



