" RODENTIA—GEOMYINAE—GEOMYS BREVICEPS. 379 
Measurements. 
eee oa 
Nore too0tol tat) == sn sacenn sce ans -nn nano age cssesecscnce| 6 9 
Tail, from root to end of vertebra, uncertain-......-..---------- 2 2 
short haired: portion, uncertain...---=-..4.-----.2.---.-- | 1 8 
Arnnorp sop co end Gf Cla Wasscces coco esne sed sceessccewacces 1 14 
SRERESE SSS ES RV a ee ee |--2---+----- 6 
and. without! Claws 22.2 Soe cs Soe oh nnn fe tee sce cee week {Were Se oe ae oe 83 
Gini coa Per: SWOT CLAN = ae aint ae ale noe mittee alee = ae ai 32 
RECON CC] Wire oath ale ee ee ale le learn ele i a 34 
Tis finperios = co oete eet eae eae Se eee coe oeae (See ass eS 2 
fourth’ Claw: =so04-- + =saecesceses steer wsslaccauasseoes |see eons canes 
Lbs hupere (between third) ea 2- hese Socios ec 23 
SkolMlencih@ss-eaeon ete seremes Seite no Utes ould 1.564 «sb soko soe 
ois ki Ra hee ae En oe ee ee eae A988 | ees ae 
As stated, this species exhibits considerable resemblance in color to G. bursarius from St. Louis. 
The tint is, however, more uniform on the back and sides, without the concentrated wash on the 
dorsal region. The color is rendered deeper, too, by the darker tips to many of the hairs. Beneath, 
the colors are more grayish, and the whole lining and edges of the cheek pouches, with the throat 
and chin, are whitish, instead of showing a good deal of chestnut. The inequality in the position 
and length of the digits is much greater; thus, in the St. Louis animal, the 2d finger is not 
much shorter than the fourth, though its claw is much smaller; in this the claw, even of the 
second finger, reaches but little beyond the end of the fourth finger. The greatest differences 
are, however, discernible in the skulls. In the present species they are broader in proportion ; 
especially behind, and the widest portion of the zygomatic arch, instead of being at the end of 
the zygomatic process of the upper maxillary, with the zygomata converging in straight lines 
behind this point, is really considerably further back, owing to the greater extension laterally of 
the zygomatic process of the temporal with the convex outlines of the zygomatic arch. The 
- forehead is much flatter and the snout shorter. The teeth are also different ; the isthmus between 
the lobes of the anterior upper molars, instead of connecting the middle of these lobes, passes 
inside of the middle, exhibiting a shorter sinus inside than out. The posterior upper molar is 
more rounded or nearly circular with the angles obsolete. The molars of the lower jaw are 
much larger, especially the anterior one. The coronoid process stands a good deal higher and 
its axis more vertical. 
The skull of the present species resembles quite closely the one figured by Waterhouse in 
Charlesworth’s Magazine as Geomys umbrinus. 
The absolute determination of the species of Geomys, as of many other American animals, is 
a matter of much uncertainty, in consequence of their wide range, and the difficulty of getting 
enough materials for satisfactory comparison. Since the article on G. breviceps was written, I 
have had the opportunity of examining several other specimens, probably referrible to this 
species, from quite remote localities. One of these, from western Texas, Llano Estacado, col- 
lected by Oaptain Pope, is quite similar in every external character, but the teeth are narrower, 
