115 



species build so many in the forks of trees, being used only as tem- 

 porary summer-houses. This Squirrel is not known to migrate in com- 

 panies; they sometimes cross open country, like other Squirrels, in 

 search of food. 



It is the shyest of our species; if chased it does not stop on branches 

 or take to the nearest tree, but runs at once to its hole. They are ex- 

 tremely active, rarely lying lazily sunning themselves, as does the Gray 

 Squirrel. Their long bushy tails are in constant motion, as they spring 

 from limb to limb apparently for mere sport. 



Genus Tamias Illiger, 



Sciurus, in part, of most early authors. 



Tamias, Illiger, Syst. Mamm. et Avium, 1811, 83 (type' Sciurus striatns, 



Linnaeus^ 

 Tenotis, Rafinesque, Amer. Month, Mag:, i, 1817, 362. 



Generic Characters. — ^Skuil narrowed anteriorly; postorbital processes 

 long, very slender, directed downward and backward; plane of malar 

 bone more oblique, and zygomatic process of maxillary more expanded 

 and depressed than in Sciurus, but rather less so than in Spermophilus ; 

 anteorbital foramen oval, situated in the base of the zygomatic process 

 of the maxillary; upper premolars two or one — when two, the ifirst usually 

 minute ; ears of medium size or small, well clothed, but never tufted ; 

 cheek pouches large ; pollex with a well developed nail ; tail shorter than 

 the body, flattened and rather broad, shorter and much narrower than in 

 Sciurus ; pelage generally full and soft ; dorsal surface with two (usually 

 four) longitudinal whitish stripes bordered on each side with a stripe of 

 black, and with, except in one species, a central dorsal stripe of black, 

 known from the smaller species of Spermophilus by the absence or 

 rudimentary character of first upper premolar; weaker and relatively 

 smaller dentition; more delicate and papery skull and more flattened 

 tail ; known from Sciurus by the more slender lower jaw, capacious cheek 

 pouches, and shorter and narrower tail. 



As above defined, Tamias includes four species, T. striatus, T. asiaticus, 

 with several localized sub-species, T. harrisi, and T. lateralis. All are 

 confined to North America except asiaticus, which ranges also over a 

 large part of northern Asia and eastern Europe. 



Tamias striatus (Linn.) Baird. 

 Striped Ground Sqxtirrbl ; Chipping Squirrel ; CmPMUNK; also Chipmock. 



1731. Sciurus striatus, Catesby, Carol., ii, 1731, 75, pi. Ixxv. — Linnaeus, 

 Syst. Nat., 1758, 64.— Schreb., Saug., iv, 1791, 791.— Erxleben, 



