LAGOMYS SPELAUS, se ISS 
in the Hare; the number of molars is thus reduced in the 
Lagomys to five on each side of the upper jaw, instead of 
six, as in the Hares; and it is precisely this sub-generic 
distinction that the fossil from Kent’s Hole demonstrates. 
This fossil agrees in size with the corresponding part of 
the skull of the existing Siberian species, called Lagomys 
pusillus, but it resembles more in its configuration that 
of the Lagomys alpinus, which is the larger Siberian 
species ; the fossil presents, for example, a less relative 
depth of the fore part of the alveolar process of the upper 
jaw, than in the Lagomys pusillus ; the characteristic de- 
scending obtuse process (a, fig. 82) of the malar bone over- 
hangs in a greater degree the alveolar process than in the 
Lagomys pusillus : the upper border of the zygoma is slightly 
convex in the Lagomys speleus, not concave as in the 
Lagomys pusillus: the suborbital foramen beneath the 
vacuity in the nasal process of the maxillary is relatively 
larger than in the Lagomys pusillus, and is divided on both 
sides of the face by a slender osseous bar, which makes it 
double. 
Pallas alludes to the idea entertained by some Naturalists 
of his time,* that the Cavies of South America were modified 
Hares or Rabbits, and he saw that the transmutation 
theory might be more plausibly applied to the Siberian 
leporine animals, which, retaining the essential character 
of the dentition and internal organization of the Hare, but 
with curtailed ears and shorter hind legs, have entirely 
lost the small trace of tail which that animal possesses. 
The great naturalist of Asiatic Russia remarks, however, 
with his wonted sound judgment: — ‘Sed non est ea 
* See Buffon’s Histoire Naturelle, “ Dégénération des Animaux,” tom. xiv., 
. 372 ; who does not, however, admit the application of the hypothesis of transmu- 
Pp > y 
tation to the South American Rodentia. 
