Sinemet 
1871,] 93 [Cope. 
ERETHIZON, Cuv. 
The remains of a porcupine of the existing North American genus 
occur in the deposit. It is evidently different from the recent H. dorsatum 
and presents the following characters. 
ERITHIZON CLOACINUM, Cope. 
Species nova. 
Represented by a last superior molar of the left side, and a portion of 
one of the inferior incisors. The former indicates the distinctness of the 
species by two peculiarities. One of these is the greater vertical depth of 
the external inflection of enamel. It is nearly as deep as the internal, 
while in #. dorsatum itis very much shallower, the internal extending 
down to the alveolar border. This appearance in the present species is 
not due to deficient attrition, for the molar in question is well worn, so 
as to leave the margins of the anterior island well posterior to the anterior 
enamel margins of the tooth. This anterior island is a transverse oval, 
slightly concave behind. 
The general form of this tooth is T shaped, with an expanded triangular 
base. The second specific character is seen here ; for while the recent 
species posesses an enamel island or annulus which occupies this space 
entirely, the #7. cloacinum exhibits two, the additional one being on the 
inner side and smaller than the usual one. It is suboval, and occupies 
the inner posterior angle of the triturating surface, which is expanded, 
and less than a right angle. TI find no trace of this in five crania which I 
had the opportunity of examining.* The sizes of both this tooth and the 
incisor are about equal to the largest seen in the #. dorsatum. The 
enamel of the latter is not smooth, and hasa minute interrupted striation. 
Antero-posterior diameter of crown of molar m. 0076; transverse do. 
m. 0077; width anterior face of incisor m. 0055. 
Lerus, Linn. 
LEPUS SYLVATICUS, Bachm. 
Portions of crania of six individuals not distinguishable from this 
recent species. The palatal surface of one is exposed, and is longer in 
relation to its width than in arecent example. Thus in the former the 
length enters the width between the two anterior alveoli 1.2 times; in the 
latter 1.6 times. In Prof. Baird’s figure it enters 1.4 times. Some of the 
specimens are smaller, some larger than the average of our recent ones. 
One of them had an oval mass of carbonaceous matter in its mouth, 
probably the remains of its unswallowed vegetable food. 
PRAOTHERIUM, Cope. 
Molars similar to those of Lepus, rootless, with oval crowns transverse 
to the axis of the series, all simple ; masticatory surface not divided by 
median ridge, enamel boundary emarginate on the inner side. Number 
in maxillary bone? four. 
* T owe a skeleton of the Z, dorsatum from Muncy, Penna., to the kindness of my friend, Jas. S. 
Lippincott. 
