114 Trans. Acad. Sci, of St. Louis. 



lines of growth which become stronger towards the margin of 

 the aperture. Width of the outer volution at the aperture, 

 25 mm., distance from the outer lip to the opposite side of 

 the volution, 22 mm., height of the shell above the plane of 

 the aperture, 13 mm. 



Remarks. This specimen is identified doubtfully with 

 B. panneus. The types of the species are two imperfect and 

 distorted specimens from a horizon somewhat higher than the 

 Chonopectus sandstone. The better preserved of the two is 

 several times larger than the specimen here illustrated, but 

 their general form and proportions are about the same. In 

 the typical B. panneus there are three or four stronger lines 

 of growth near the aperture, but this is not believed to be a 

 very essential difference. The species may be easily distin- 

 guished from B. hilahiatus by its larger size, its larger umbil- 

 icus and the absence of the expansion of the outer volution at 

 the aperture. 



The specimen illustrated by Keyes* as B. panneus has no 

 resemblance whatever with the type of the species, and is 

 probably an undescribed form. The specimen illustrated by 

 the same authorf as B. hilahiatus, however seems to be a good 

 example of B. panneus. 



BUCANOPSIS DEFLECTUS n. Sp. 



PI. VI. f. 5. 



Shell small, subglobose, umbilicate, the volutions gradually 

 expanding to within one or two mm. from the aperture, 

 where the margin of the shell is abruptly deflected. Cross- 

 section of the volutions subelliptical ; aperture subelliptical, 

 the outer lip with a moderately shallow notch. The revolving 

 dorsal band narrow, flat on top, becoming obsolete a short dis- 

 tance from the aperture. The surface of the shell marked by 

 very fine revolving striae which become almost obsolete a short 

 distance from the aperture, and by even more faint lines of 

 growth. In the type specimen, at a short distance from the 

 aperture where the dorsal band and the revolving striae 

 become obsolete, there is a strong, transverse rounded groove 



* Mo. Geol. Surv. 5. pi. 50. f. 6. 

 t Loc. cit.pZ. 50. f. 3. 



