RODENTIA-GEOMYINAE-GEOMYS. 
371 
finer one near the inner edge ; (in Thomomys the large central groove is wanting, leaving the 
fine internal one.) The upper incisors are much curved, and describe nearly a full semicircle, 
passing round almost to the base of the root of the anterior molar. In the lower jaw the arc is 
also about a semicircle, reaching to the side of the base of the condyloid process. 
The upper molars are considerably convergent anteriorly, their inner lines intersecting (if 
produced) in the incisive foramina. They are all rootless, and diverging widely at their bases ; 
the anterior is inserted very obliquely forward, at an angle of about 45° with the axis of the 
skull; the others more and more near to the perpendicular, and curved, the convexity anterior, 
yet without becoming quite perpendicular. The lower molars are equally oblique, except that 
here the posterior is most inclined, and that backwards ; in fact, in its curvature it stands quite 
parallel to the incisor The anterior upper molar consists of two regular ellipses, much elongated 
transversely, of about equal size, and connected by a narrow isthmus which crosses between their 
middle portions, or a little interior to this ; the second and third molars succeeding are simple 
ellipses, of nearly equal size—the second rather largest, the third about equal to the ellipses of 
the first; the last molar is longer, and irregularly three, four, or five sided. The crowns of 
the first lower molars show, also, the two ellipses, the anterior smallest, the bridge at about 
the centre ; the remaining teeth are also elliptical, the posterior one narrowest. 
In the skeleton of Geomys, ( G . bursarius, No. 1160,) we find the limbs, though short, to he 
quite massive, the anterior indeed appreciably stouter than the posterior. The vertebral 
column is short, but the component vertebrae broad and firmly knit together. The neck is very 
short, its seven component vertebrae measuring only about T 3 F the length of the skull. The 
second cervical vertebra is large and massive, with a compressed short upper spinous process. 
The vertebral formula is 1 cervical, 12 dorsal, 1 lumbar, 5 sacral, and 11 caudal. The posterior 
two sacral vertebrae have their transverse processes anchylosed and expanded so as to come into 
firm union with the ossa innominata, leaving a wide foramen on each side of the spine, between 
this junction with the sacrum and that anterior to it, in which the first and second sacral are 
involved. The bones of the fore leg are stouter than the hinder. The olecranon process is 
much lengthened, its projection behind the centre of the joint being nearly one-third the whole 
length of the ulna. The clavicles are well developed. The tibia and fibula are united a little 
below the middle of the former, and diverge widely above. 
The species of Geomys are confined to the regions east of the Eocky mountains, and, in fact, 
have not yet been observed much west of the -Mississippi, or near the mountains. They are 
very abundant in Missouri, Iowa, and southern and western Illinois ; they exist also in Texas 
and all the Gulf States. Florida and Georgia also possess one, possibly two, species, but none 
have yet been found on the Atlantic coast north of the Savannah river. Southward they reach 
into Mexico, and, possibly, as far as Central America. 
The species are termed “ gophers” in the west, but in Georgia and Florida they are almost 
universally called “ salamanders.” Where this latter name is prevalent the term “ gopher” 
is equally well understood to mean the large land tortoise, Testudo polyphemus, to which the 
Savannah river also serves as a barrier. When either of these names is used, therefore, by any 
individual, it becomes necessary first to ascertain his region of country before it can be told 
whether a mammal or reptile is in question. 
From the list of synonymes at the head of this article it will be seen that many genera have 
been proposed for the gophers. The first, in point of date, is Diplostoma , of Kafinesque, based 
on reported characters of the Missouri species. With several accurate indications, we are told 
