392 Hall and Wyman on 
the first identical with the existing European species, and the 
second about one fifth larger. 
® Remains of the Castoroides Ohioensis, consisting of an 
imperfect half of a lower jaw, an incisor tooth of the upper, 
and a radius, were first brought to the notice of the scientific 
world by Mr. J. W. Foster, one of the assistants in the geo- 
logical survey of. the State of Ohio; they were exhumed: in 
company. with a. cranium belonging to the genus Ovis, molar 
teeth and bones of Mastodons, elephants and other animals.’ 
The generic characters deduced from these remains, by: 
Mr. Foster, are as follows: “'Teeth — incisors, } 1, destitute of 
canines; molars, * 4; total, 20; incisors of the lower jaw, con- 
vex in front, and longitudinally striated ; posterior surface: 
angular, smooth, and slightly concave. The grinders are 
obliquely traversed by six ridges or folds of enamel.” ‘The 
oroides was an animal closely allied. to the beaver, but 
far surpassing it in magnitude ; its life was probably aquatic; 
and its food consisted of vegetable substances, which it 
gnawed off with its powerful incisors.” ? 
An accurate cast of the lower jaw above described,’ was 
made, and now exists in many museums in the United States. 
On comparing this cast with the lower jaw of the cranium 
now under consideration, no question can exist as to their 
belonging to one and the same species ; but on reviewing the 
generic characters given by Mr. Foster, as will be seen here- 
after, they will be found insufficient to characterize the genus; 
and as regards the molar teeth, his description is not in aC 
cordance with the anatomical peculiarities of those organs. 
1 Second Report on the Geological Survey of the State of Ohio, p. 81, et seq. ; 
Am. Journ. Science, Vol. XXXI. p. 80. 
? From a notice of th ins in the American J Lof Science, Vol. XXXL 
p.80, it would appear that the radius was ten inches in length, two inches across 
ur "X ^ 
extremities, however, were mutilated. The lower incisor was mu less cur 
than the upper, and has a length. of nine inches: the lower jaw itself measwe 
eight i - : 
