SCIURIDA—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 Sciuride. 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 
“Oynomys 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 Anisonyz, 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 “‘Sewellel” under the name Anisonyx rufa, which belongs to a wholly 
different family (Haplodontide). '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, is preoccupied by Cynomys. 
The first species referred to it is the Anzsonyx 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 far 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 nuts. 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 Artemisia, Obione, ete. Where the eastern C. ludovicianus 
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 
Sciuridae. 
