NATURAL SCIENCES OP PHILADELPHIA. 425 



Pled kotom aria Hitronensis, n. sp. Shell rather large, depressed-turbinate, 

 consisting of about four very rapidly enlarging whorls. Body whorl flattened 

 from above, moderately convex above ; the base a twisted plane bounded on 

 one side by the slope into a large open umbilicus, on the other, by the sharp 

 prominent carina which marks the periphery of the whorl. Surface of the 

 whorl marked by eleven raised plications and intervening broad sulci, of which, 

 counting from the umbilicus, the sixth rests upon the carina, and the eleventh 

 is close to the suture. These are crossed by striae of growth rising from the 

 umbilicus, stretching far forward upon the base, curving backwards just be- 

 fore reaching the carina, and apparently curving forward again after pass- 

 ing it. 



Height of shell 1-00 (100) ; diameter of base 2-00 (200) ; transverse diame- 

 ter of aperture -92(92). 



Locality. Light-house, Pt. aux Barques, in intercalated sandstones of the 

 Huron group. 



This species recalls Euomphalus carinatus, Sow., (Murch. Sil. Syst., 610, pi. 

 vi. fig. 10). 



Dentalitjm, Linnaeus. 



Destalidm ? Barquense, n. sp. Shell small, very gradually tapering, 

 slightly compressed. Surface of cast smooth. Surface of shell unknown 

 apparently striate or grooved transversely ; shell-structure prismatic, the 

 axes of the prisms being normal to the surface of the shell. The shortness 

 of these prisms gives the structure the appearance of miniature mosaic. Di- 

 ameter of fragment *06. 



Locality. Pt. aux Barques, in a stratum overlying the gritstones. 



Bellerophon, Montfort. 



Bellerophon rugosiuscplus, n. sp. Shell of moderate size, globoid, very 

 i apidly enlarging ; umbilicus rather broad and deep, but not perforate only 

 one whorl being exposed to view. Transverse section somewhat rhomboidal, 

 with rounded angles, becoming more rounded with age. Keel in the young 

 shell rather prominent, but obtuse, becoming more depressed with age, until 

 finally the dorsal surface is regularly rounded, and the sides have developed 

 some obliquely longitudinal folds winding into the umbilicus. Aperture trans- 

 versely expanded, subreniform. The entire surface, except the peripheral 

 belt, is marked by direct, longitudinal raised striae, separated only by a nar- 

 row groove ; these are crossed by a set of transverse striae, which, on the um- 

 bilical slope are somewhat irregularly waved and more pronounced than on 

 the dorsum ; on passing the lateral angle they divide irregularly and result 

 in a set of finer stria?, which are abruptly reflected in approaching the keel, 

 and in the older portion of the shell, gradually disappear before reaching it, 

 while in the young shell they meet upon the keel in an acute angle of about 

 58. Cast nearly destitute of ornaments. 



Diameter of large specimen "77 (100) ; height of last whorl to the middle of 

 the umbilicus *52 (6S) ; height of aperture -36 (47) ; width of aperture - 54 

 (70) ; number of longitudinal stria? in one-tenth of an inch 8 ; number of 

 transverse striae in one-tenth of an inch, counted on the umbilical slope 6, 

 counted on the keel 12 to 15. 



Localities. Marshall and Sees. 19 and 26, Liberty, Jackson county. 



The general appearance of this shell is that of B. decussatus, Flem., but a 

 careful examination of all the figures and descriptions in my possession, has 

 convinced me that it is a distinct though representative species. Want of 

 space, however, forbids offering the comparisons. 



Var. taniatus. This well-marked variety (perhaps distinct species) is the 

 form which approaches nearest to Sandberger's B. decussatus. It differs from 

 the usual forms of the present species in having a less depressed dorsum and 

 a smaller transverse diameter ; a more prominent keel which is bounded by 

 a slight elevation along each margin, and in its finer striae, especially on the 



1862.] 



