658 TRANS. OF THE ACAD. OF SCIENCE. 
tuse angle; the lower edge of each whorl projects a little be- 
yond the upper edge of the whorl below; the lower and out- 
er surfaces are ornamented with numerous unequal revolving 
striw, crossed by transverse strie oblique, and parallel to the 
margins of the aperture; those on the lower surface more or 
less sigmoid; aperture oblique, subrhomboidal. 
Height, 3.25; width of base, 3.85. 
This rare species is perhaps the largest known Trochus. It 
still retains its pristine luster and gracefully cancellated sur- 
ace. It very much resembles 7. marmoratus, Lam., of the 
present seas; but it has fewer whorls, a broader and more 
concave base, finer and more delicate markings. 
The magnificent specimen before me was discovered by 
Col. Wm. Gilpin in the Coal Measures of Jackson county, 
and was presented to Dr. Norwood for the State Collection. 
LitToRINA WHEELERI, N. sp. 
Shell small, subglobose, granulated. Spire short, depres- 
sed; whorls three, convex ; the last large and inflated; su- 
ture impressed ; aperture slightly oblique, oval ; surface cov- 
ered with small semiglobular granules, each of which has a 
slight depression in its summit. 
Length, .27; breadth, .23; length of aperture, .19; breadth 
of aperture, .14. 
This unique little shell was discovered by Mr. Broadhead, 
in the Coal Measures of Monroe county. 
CEPHALOPODA. 
Navtitus Laws, n. sp. 
Shell very large; septa very numerous and very convex; 
volutions depressed on the dorsal surface, somewhat flatten- 
ed on the sides, and flattened or concave on the inner sur- 
face ; taper gradual; aperture elliptical. 
Diameter of the shell, 10.75 inches; length of aperture, 4 
inches; width, 3.25. $ 
This large and very rare fossil was discovered by President 
Laws of Westminster College, in the lower beds of the 
argin; whorls 
Whorls few, 
