NATURAL SCIENCES OF PHILADELPHIA. 
425 
Pleurotomaria Huronensis, 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 ttie 
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 strife 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., 616, pi. 
vi. fig. 10). 
Dentalium ; Linnaeus. 
Dentalium ? 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 rugosiusculus, n. sp.—Shell of moderate size, globoid, very 
rapidly 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 striae, 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 ef 
the umbilicus *52 (68); height of aperture *36 (47) ; width of aperture *54 
(70) ; number of longitudinal striae 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 Secs. 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. tfeniatus. 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 strise, especially on the 
1862.1 i... I 
