SCIUKIDiE— CYNOMYS. 891 



In Cynomys, the edges of the orbits are raised above the plane of the 

 frontals, as in several of the species of the subgenus Colobotis, but rather 

 more strongly, and the anterior face of the zygomatic process of the maxillary 

 is deeply excavated. The breadth of the skull at the posterior border of the 

 zygomatic arches is equal to or greater than the length of the skull, exclusive 

 of the portion anterior to the front edge of the maxillaries, and hence much 

 greater than in any other genus of the Sciuridce. All the teeth are relatively 

 large and heavy ; the grinding teeth are narrowed on the inner border, as in 

 Spermophilus and Arctomys. The molar series occupy about one-third the 

 entire length of the skull. The incisors are short and strong, with the antero- 

 posterior breadth nearly twice the transverse.* 



The genus Cynomys was proposed by Rafinesque in 1817, and based 

 wholly on the description of the "Barking Squirrel" of Lewis and Clarke, 

 which he named Cynomys socialis. He also doubtfully referred to it a 

 " Cynomys grisea", based on the "Petit Chien" of the Upper Missouri, inci- 

 dentally mentioned by Lewis and Clarke. This is merely another name for 

 the Barking Squirrel of the same authors (= Arctomys ludovicianus Ord,= 

 Cynomys ludovicianus Baird). In the same article (and on the same page), 

 Rafinesque also proposed the genus Anisonyx, based primarily on the descrip- 

 tion of the "Burrowing Squirrel" of Lewis and Clarke (= Arctomys colum- 

 bianus Ord,= Cynomys gunnisoni Baird), but which was made to include also 

 their "Sevvellel" under the name Anisonyx ritfa, which belongs to a wholly 

 different family (Haplodonticke). The genus is based on wholly false charac- 

 ters, resulting from Rafinesque's misinterpreting Lewis and Clarke's descrip- 

 tion, and, as far as the present group is concerned, *s preoccupied by Cynomys. 

 The first species referred to it is the Anisonyx brachiura, equal to the Arctomys 

 columbianus of Ord of two years' earlier date, based on the same description. 



The genus Cynomys is restricted to the parks and plains of the great 

 Rocky Mountain Plateau, and is represented, so for as known, by only two 

 species. 



* The food of Cynomys consisting of soft herbaceous plants and grasses and succulent roots, the large 

 size of the teeth and their very firm implantation offer a puzzling problem. The great antero-posterior 

 breadth of the incisors, the heavy, strong molars, and all the provisions of the skull for muscular attach- 

 ment indicate great strength of jaw and cutting power— far greater even than in the true Squirrels, 

 whose food consists largely of hard uuts. The species of Cynomys live on the open, barren plains, gen- 

 erally where the coarsest plants are annuals, with stalks rarely thicker that one's finger, and the only 

 suffruticose vegetation is the various forms of Arhmisia, Obione, etc. Where the eastern C. ludovicianun 

 most abounds, there is apparently nothing for it to feed upon requiring great strength of jaw or heavy 

 dentition. Yet it presents the heaviest dentition and greatest masticatory power met with among the 

 Sciuridoe. 



