FAMILY CASTORIDA). 
75 
(EXTRA-LIMITAL.) 
(fossil.) 
PLATE XIX. FIG. 3, A, li. 
C. (Trogonthcrium?) ohiocnse. This species, which belonged to an animal nearly six feet in length, 
is founded on the lower jaw of the right side, found near Nashport, Licking county, Ohio, and now 
in the Zanesville Atheneum. From a cast in the Cabinet of the Lyceum, we are enabled to give 
the following dimensions: Length, in a straight line, from the posterior part of the lower jaw to the 
tip of the incisor, 9*5; length of the denuded incisor, following its curve, 9*5; of its bevelled tip, 
1*6; breadth of the same, 0*6; breadth of molars, 0 *5. The incisor is traversed through its whole 
length on its anterior and exterior surface, by deep parallel longitudinal grooves. The molars are 
nearly equal, the penultimate smallest. In some respects, it appears allied to Hystrix. It is, as far 
as we know, the first instance of the discovery of a fossil of this order in America, and is certainly 
one of the largest known. In the loose strata near the Sea of Azof in the neighborhood of Tagan- 
rok, a skull has been found, which was at first attributed to the Beaver, and which bears a strong 
resemblance to our specimen. Mr. Fischer has described it as the type of a new genus, which he 
calls Trogontherium, but I have not been able to find his description. For further particulars in 
relation to the Ohio specimen, see the American Journal, Vol. 31, p. 80, (figure) 
GENUS FIBER. Illiger. 
Tail long, narrow, pointed and vertically compressed. Molars twelve, the crowns exhibiting 
sections of triangular prisms. Toes of the hind feet partially webbed. Teats six. 
THE MUSQUASH. 
Fiber zibethicus. 
PLATE XX. FIG. 2 —PLATE XXXII. FIG. 3. Skull. — (STATE COLLECTION.) 
Castor zibethicus. Linn. 12 Ed. p. 79. 
Mush Beaver. Penn.* Arct. Zool. Vol. 1, p. 106. 
Fiber zibethicus. Harlan, Faun. p. 132. Godman, Am. Nat. Hist. Vol. 2, p. 58, figure. Richardson, F. B. A. Vol. 1, 
p. 115. 
Muskrat. Emmons, Mass. Report, 1840, p. 54. 
Characteristics. Dark brown above, tinged with reddish ; greyish beneath. Length eighteen 
to twenty inches. 
Description. Body robust and thickset. Head short, somewhat arched above. Muzzle short 
and obtuse, with rigid whiskers on each side. Eyes small and black. Ears low, rounded, 
broader than high, covered with hair, and nearly concealed in the fur. Neck short and indis¬ 
tinct. Fore feet short, with five claws, and covered with short glossy hairs to the bases of the 
nails, which are short, compressed and slightly curved; the thumb distinct, and furnished 
