CARBONIFEROUS AND PROTOZOIG SPECIES. 581 
SCAPHITES (AMMONITES?) NODOSUS. (N. 8.) 
(Tab. VIIL, fig. 4.) 
Specific character.—Shell large* and ponderous. Volution subcylindrical, enlarging gradually towards 
the terminal chamber. Surface ornamented with sinuous coste, most of which bifurcate at different 
distances from the umbilicus, and thus multiplied, proceed across the dorsum. Two rows of very promi- 
nent tubercles. The row near the periphery especially large and prominent, and from one-half to three- 
quarters of an inch apart. Aperture subovate. Serrations of sutures represented, fig. 4,a. Greatest 
diameter, four inches ; greatest thickness, two and a half inches, 
It is associated on Sage Creek, a southern tributary of the Cheyenne, with Jnocerami of huge dimen- 
sions, one of which is represented by the medal-ruled plate, Tab. VIII. a. 
GYROCERAS BURLINGTONENSIS. (N. 8.) 
(Tab. V., fig. 10.) 
Specific character.—Scroll-shaped ; yolutions about two, rapidly enlarging ; chambers forty-cight (?), 
indicated by undulating lines curving from the inner margin to the periphery. 
This Gyroceras is of unusually large dimensions,—about fifteen inches in diameter, and nearly three 
feet along the dorsal circumference of a single coil. It occurs in the oolitic bed, at the top of member a, 
of the Lower Series of Carboniferous Limestones, under the encrinital beds of the quarries at Burlington, 
Towa. 
DISCITES TUBERCULATUS. (N. 8S.) 
(Tab. V., fig. 14.) 
Specific character.—In the character of the volutions, general form, and contour of the shell, this fossil 
resembles Nautilus (Discites) subsulcatus of Phillips, but differs in the back not being concave along the 
middle, but flat ; also in the presence of a row of tubercles on either side of the flat dorsal surface 3 neither 
is there any concavity of the sides towards the outer edge. 
Locality.—Iowa Point, Missouri River, in carboniferous limestone. 
GASTEROPODA. 
PLEUROTOMARIA MURALIS. (N. 8.) 
(Tab. IL, fig. 6.) 
Specific character.—Obtusely conical; convolutions five to six, with nearly vertical sides, like a spiral 
wall; upper surface of the whorls deeply channeled, and doubly carinated; undulating striae, transverse 
to the convolutions. Height about two-thirds of the width. 
From the Magnesian Limestones (F. 8) of Red River of the North. 
STRAPAROLLUS (EUOMPHALUS) MINNESOTENSIS. (N. 8.) 
(Tab. IL., figs. 12, 13.) 
Specific character.—Flatly turreted above, deeply umbilicated beneath; convolutions about three, 
sharply angular, and carinated around the periphery, with a shallow canal on the upper surface ; aperture 
small and subrhomboidal; 13 inches in diameter. 
From the Lower Magnesian Limestone (F. 2), Traverse des Sioux, Minnesota. 
* This is by far the largest boat-shaped concamerated shell that has ever come under my observation. 
