MURIDM 



915 



Genus Citellus Oken, 181 6. 

 Synonym. — Spermophilus^F. Cuvier, 1S2 5; C itelhis 'Lichtenstein. 

 Definition. — As above. 



Type S'geGies— -Citellus citellus L.innseus, 1766. 



We are, however, concerned with C. beecheyi and with M. hobak. 



Citellus beecheyi Richard, 1829. 



Definition. — Citellus of large size with large prominent ears. Tail more 

 than two-thirds of body-length. Colour above mixed black and pale yellowish 

 brown. 



Remarks. — This is the ground squirrel of California mentioned above. 



Genus Marmotta Blumenbach, 1779. 

 Synonym. — Arctomys Storr, 1780. 

 Definition. — As above. 



Type Species. — Marmotta marmota Linnaeus, 1758. 



Marmotta bobak Miiller, 1 776. 



Definition. — Marmotta of medium size resembling the type, but of uniform 

 colour, being above yellowish-brown, overlaid with black. 



Remarks. — This is the tarbagan of Mongolia and Central Asia. 



Family Murid.^ Gray, 1821. 



Rats and Mice. 



i?he genera of the Muridse, which concern us, may be recognized as follows : — • 



A. Crowns of grinding teeth, with tubercles arranged in transverse rows. 



I. Rows of tubercles in grinding teeth three, very distinct in upper 

 jaw; tail long and scaly. Subfamily Murines (Old World rats 

 and mice). 



II. Rows of tubercles in grinding teeth two; tail generally hairy. 

 Subfamily Cvicetince (American rats and mice). 



B. Crowns of grinding teeth divided into raised loops or triangles o^ 



enamel, not tubercular. 

 I. Upper front teeth narrow, compressed, each one thicker than 

 wide at base; body not clumsy; tail always long; eyes and 

 ears large and prominent. Subfamily Nsotomince (wood rats 

 and cave rats)- — -Neotoma. 

 II. Upper front teeth broad, each one wider than thick at base; 

 bodyclumsy; tail short; eyes and ears small and inconspicuous. 

 Subfamily MicrotincB (voles and lemmings). 



Subfamily Murinse Blaird, 1857. 

 Definition. — As above. 



Remarks. — The Murinae comprise the genus Epimys Trouessart, 1857, to 

 which belong the rats and mice, of which two are of great importance in the 

 spread of plague — viz., Epimys rattus and E. norvegicus. 



Genus Epimys Trouessart, 1857. 



Definition. — Murinse with first and second upper molars, with two tubercles 

 on inner side. Upper incisors with outer cutting edge entro. 



Epimys rattus Linnaeus, 1758. 

 Synonym. — Mus rattus Linnaeus. 



Slender rats with very pointed muzzles and large out-standing ears, large 

 prominent eyes, long tail, and greyish-black fur. 



