3 74 The Extinct Rodentia of North America. [April 
derful bone deposit known as “ fossil lake ” in the Oregon desert 
I cannot distinguish it from that of the Zhomomys bulbivorus, now 
living on the borders of that region. 
Professor B. F. Mudge discovered the skull of a large species 
of the genus Geomys in the sands of the Blue river, Kansis, 
which I cannot distinguish from a living form. 
CAS. | oiae 
+ 
ANN ” 
™ 
b . 
c WAS Mo’ 
Fic. 25.—Diagrams of molars of Arvicolæ, from the bone cave at Port i ! 
Penna., enlarged. 0. 16, A. involuta Cope; No, 17, A. sigmodus Cope; 
A. hiatidens Cope. From Proceed. Am. Philos. Soc. 1870. 
AMBLYRHIZA Cope. 
This remarkable genus of rodents was. first detected by me 
found in the West Indian island of Anguilla. I have since p 
molars of a species of the genus in a collection in Charleston, 5 
Carolina, showing that it extended its range to the continent, @ 
must be included in our Pliocene fauna. 
In the year 1868 a quantity of cave earth, limestone ce 2 
and bone breccia were brought to the port of Philadelphia E 
a cave in the small Antillean island of Anguilla, which 0° >. : 
to Denmark. Through the attention of Mr. Waters I leant 
the existence of fossil bones in the cargo, and proc rather 
examine them. Remains of long bones lying irregularly ee 
hard but cavernous red cave deposit of limestone, Wer walls é 
mingled with fragments of lighter limestone from the E 
the cave in irregular masses, the whole being penetrated $ 
mixed with a yellow stalagmitic deposit of arragonite. a 
From a block of the breccia I dressed three molar e | 
partially complete, and two much broken incisors, frag™ a 
maxillary and pelvic bones, shafts of various long bones, ae 
