204 CASTORID &. 
birds; and in masticating the bodies of these small animals 
with their coarse conical teeth, many bones and fragments 
of bone would be pressed outwards through their lips, and 
fall neglected to the ground.” 
Whatever cause may have operated on the introduction 
of the numerous Water-rats into the Kirkdale Cavern, a 
similar effect has been produced in many other caverns, 
both in this and other countries. Dr. Schmerling has 
figured characteristic remains of both large and small 
species of Arvicola from the caverns of Litge. The speci- 
mens of upper and lower jaw of the Arvicola amphibia, 
figured at the head of the present section, are amongst 
several specimens of this species from the cave of Kent’s 
Hole, some of which are now in the British Museum. 
Remains of the <Arvicola amphibia, (lower jaws) were 
found in the ossiferous cavern at Berry Head, Devon. 
Some of the bones from the cavernous fissures at Oreston, 
show marks of nibbling, which may be referred more pro- 
bably to the incisors of a small Rodent, than to the canines 
of a weasel.* 
Cuvier, to whom both specimens and drawings of the 
Arvicola from Kirkdale were transmitted, acknowledges 
that the jaws and teeth agree in size and other characters 
with the common Water-rat, but he found the other bones 
to be a little smaller, which led him to suspect that the 
species was not the same; but he adds that an entire 
skull of the fossil Arvicola could alone determine the ques- 
tion. So desirable a specimen has not, hitherto, been ob- 
tained from any British cavern. An os imnominatum, the 
characteristic anchylosed tibia and fibula, and some verte- 
bre of the Arvicola from Kent's Hole, are not inferior in 
size to those of the existing Water-vole, with the dental 
* See ante, p. 118. 
