870 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
and on Seba’s “ Sciurus, rarissimus, ex Nova Hispania, teniis albis”,* together 
with references to Brisson, Pennant, and other early authors, whose accounts 
are based wholly on Fernandez and Seba. Erxleben’s Securus mexicanus has, by 
several writers, been considered as identical with the Citellus mexicanus of Lich- 
tenstein; but Fischer, as early as 1829, and hence before Lichtenstein described 
his Citillus mexicanus, suggested that Erxleben’s Sciurus mexicanus might be 
referable to the Sciurus (Tamias) striatus of authors. While Fernandez’s 
“Tlamototl”, and also Seba’s animal, judging by both his figure and descrip- 
tion (disregarding altogether its impossible tail), may be referable to Spermo- 
philus mexicanus, the introduction of this species into thé annals of natural 
history cannot with certainty be carried back beyond Lichtenstein’s detailed 
description and excellent figure. It has since been well figured by Audubon 
and Bachman, while Baird’s further account of it leaves little now to be added, 
especially since no specimens additional to those used by Professor Baird are 
at present accessible. The only synonym that appears to have thus far arisen 
is the spilosoma of Audubon and Bachman, who erroneously referred the 
young of S. mexicanus to that species, and finally thoroughly confounded the 
two species. 
It is chiefly a Mexican animal, but is quite abundant on the Texan side 
of the Rio Grande; it has not, however, been reported from further north- 
ward. Nearly all the specimens in the collection of the National Museum 
are from the vicinity of the Rio Grande. It probably ranges far southward 
over the plains of Eastern Mexico, Audubon and Bachman stating that they 
had been informed of its occurrence as far southward as the province of 
Vera Cruz. 
TasLe CXV.—Measurements of two skulls of SPERMOPHILUS MEXICANUS. 
| wl caleuele 6s |8 
| : z S |e les 2 |e 
| z a/1€|2 |24| s lag|3 
re as gS Ne ISS se crn 
u 5 | at a g Baa a} Eo} wo s 
S a oo 2 > ¢ so 2 =) a ee) 
4 A F : s a = cn Rel/ a |73/2e Ee ic 
Fi 3 Locality. Saltese ze | = EB e |Z Be) 2 IS ele A % 
FP }| a a o oD oa Cae |S $8 S |23i8 4 a 
o | a hele easiest uall ely an lspe este etsy iy cera TS |] 
& | 2 Sellers Se Cea Eee eG, ise ce ey | 2 
<4 | = 2 a = e 2 welod be we Ole > be be 
& = e | 3s = re me Noes res | Saye eS. | feecucees iter el lire ae 
g a Ss 3 = 2 a 2 |Re)/e5| 2 |aeleas|] & E 
a | ° = Be Cy Cy 3 a i a arias 6 o 
ey] 2 <] 5 A A A 4 |p =) ==) =) i | 
1441 | “cere Laredo, Nex 2225-5 58c-. =: 1.75 | 1.00 | 0.35 | 0.55 | 0.18 | 0.30 | 0.55 | 0.95 | 0.21 | 0.17 | 0.35 | 1.00 | 0.46 
1652 | 203 | Pesquiera Grande, Mexico} 1.65 | 0.93 | 0.35 | 0.57 | 0.17 | 0.30 | 0.50 | 0.87 | 0.25 | 0.15 | 0.30 | 0.90 | 0.46 
* Thesaurus, vol. i, p, 76, pl. xlvii, fig. 2, 1734. 
