PALEONTOLOGY. 129 
Pecten (Monoris?) CoLoRaDENs!s, (n. sp.) 
Plate I, fig. 6 and 6a. 
Shell of moderate size, (two inches in diameter,) sub-orbicular, oblique; slightly lobed on 
posterior side; anterior ear rounded? small? posterior ear prominent, with a straight hinge- 
line and flexuous lateral margin; apicial angle, 85°; surface bearing 18-19 radiating coste, 
which are straight and strongly marked on the anterior and middle portions, and become 
slightly curved and gradually smaller as they approach the posterior side, on the lobed expan- 
sion of the shell becoming entirely obsolete. These carinations are crowned at intervals 
somewhat greater than their breadth by prominent arched lamellw, by which the surface is 
highly ornamented and roughened. 
This is a beautiful fossil, apparently quite distinct from any species of Pecten or Monotis 
hitherto described. 
The details of structure are not sufficiently well preserved in my specimens to enable me to 
determine certainly to which of these genera it should be attached, the characters which it 
exhibits being such as are shared by both. 
The posterior ear is flat, broad, and apparently angular, bordered by a straight line on one 
side; the other flexuous and pecten-like. The anterior ear is partially wanting, but is evi- 
dently narrow, and probably rounded. The straight hinge-line of the opposite wing is not 
continued beyond the beak. 
FUSILINA. Fisher. 
FUSILINA CYLINDRICA. Fisher. 
This fossil, which is found in the Carboniferous or Mountain limestone in different parts of 
Europe, though, so far as‘I am aware, not yet discovered in the Alleghany coal-field, is exceed- 
ingly abundant in the Carboniferous rocks of the western part of the Mississippi valley, 
where it ranges from the ‘‘ Carboniferous limestone’’ to the Coal measures. 
I did not find it in the limestones on the Colorado nor about Santa Fé, though it has been 
found at no great distance east of that point. 
After leaving the Cretaceous and Permian rocks of western Kansas, and coming into the 
Coal measures, I found it occurring in such abundance as to form the greatest part of the mass 
of some of the beds of limestone. 
The strata which contain it are interstratified with the shales and coal seams of the produc- 
tive Coal measures, and it seems to run through the entire series. 
FOSSIL PLANTS. 
CYCLOPTERIS. Brong. 
CycLoprerts MoquEnsis, (n. sp.) 
; Plate III, figs. 1 and 2. 
C. fronde simplici, stipitata, orbiculata vel ovata, cordata, saepe basi latere uno obliqua; 
nervo medio basi valido medio evanescenti; nervis secundariis tenuibus creberrimus dichotomis, 
furcatis aequalibus. Fructificatio marginalis? 
I have included this beautiful form in Cyclopteris with some hesitation, as by its strong 
median nerve it differs strikingly from any known species of that genus, and is clearly excluded 
from it by the definitions of Brongniart, Geeppert, Unger, and all other writers on fossil 
