LAGOMYS SPEL^EUS. 215 



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 

 pwsillus, 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 puslllus : the upper border of the zygoma is slightly 

 convex in the Lagomys spelaeus^ 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'a Histoire Naturelle, " Degeneration des Animaux," torn, xiv., 

 p. 37'2 ; who does not, however, admit the application of the hypothesis of transmu- 

 tation to the South American Rodentia. 



