1883. ] The Extinct Rodentia of North America. 373 
periods inthe United States. I have described a true squirrel, 
Sciurus panolius, and a chipmunk, Tamias levidens, from Virginian 
cave deposits, and have found indisputable remains of the ground 
marmot, Arctomys monax, associated with them. In the Port 
Kennedy bone cave in Pennsylvania, Mr, Wheatley found Sciu- 
rus calycinus Cope, associated with Megalonyx, etc. 
Remains of the beaver are common in the latest Tertiary 
beds, 
Morip2. 
Jaws undistinguishable from those of the jumping mouse, 
Meriones hudsonius, were found in the Port Kennedy bone cave. 
A large wood-rat, Neotoma magister, was found by Professor 
Baird in the Carlisle, Pa., bone cave. The meadow-mice (Arvi- 
cola), left numerous remains in the Port Kennedy cave, which 
represent no less than six species.! Four of these are related to the 
G. 24 —Diagrams of molar teeth of Arvicola, from the Port Kennedy bone cave, 
Pennsylvania, enlarged. No.1 3, A. speothen Cope; No. 14, A. tetradelta Cope; 
No. 15, A. didelia Cope. From Proc. Am. Philos, Soc. 1870. 
recent smaller meadow-mouse, Arvicola pinetorum ; while two, the 
A. speothenand A. hiatidens Cope, represent special divisions of the 
genus. These I have called Isodelta and Anaptogonia respectively. 
€ A. hiatidens is one of the largest species of the genus, and 
the columns of the first inferior molar are more numerous than 
in the species found with it. The inflected angles between the 
columns do not touch the sides of the opposite columns as in 
Most species of the genus. Arvicolas also occur in the Pliocene 
of Fossil lake, Oregon. : 
Saccomyipz:. 
I found an almost perfect skeleton of a “ gopher” in the won- 
1 oe 
See Proceedings American Philosophical Society, 1871, p- 87- 
