236 EXPLOEATION OF THE CANONS OF THE COLOEADO. 
GEOMYS MEXICANUS, (Licht.) Lee. 
Aecomys mexicanus, LIGHT., Abhand. K. Acad. Wiss. Berl. 1827, 113. BRANTS, Muizen, 1827, 27. WAGN., 
Suppl. Schreb. iii, 1843, 384 ; iv, pi. 206 A. CHARLESW., P. Z. S. ix, 1841, 60. SCHINZ, 
Synop. ii, 1845, 133. 
Saccophorua mexicanuq, FISCH., Synop. 1829, 305. EYD. & GERV., Gue"riu Mag. vi, 1836, 23, pi. 21, f. 5, 6 ; 
Voy. Favorite, v, 1839, 23, pi. 8, f. 5, 6. RICH., Rep. Brit. Assoc. vi, 1836, 156. GRAY, List 
Mamm. Br. Mus. 1843, 150. GERR., Cat. Bones Br. MUB. 1862, 223. 
Pscudosioma (Geomys) mexicana, AtJD. & BACH., Q. N. A. iii, 1854, 309. 
Geomys mexicanus, LEG., Proc. Acad. Nat. Sci. Pbila. 1852, 160. BAIRD.M. N. A. 1857, 387. 
Geomys (Saccophorus) mexicanus, GIEB., Saug. 1855, 529. 
Tucan of HERNANDEZ. Tuca or Tuza, MEXICAN. Tugan apnd GERR., L c. 
MexicaniscJie Taschenmaus, GERMAN. 
DIAGNOSIS. Superior incisors bisected by a single median furrow (as in 
G. casfanops, which is very different in color). Coloration and general appear 
ance of G. bursarius (which has two distinct grooves on the upper incisors). 
Fur soft, sleek, as in other species of the genus (excepting G. hispidus, where 
it is extremely coarse and harsh). Averaging much larger than any United 
States species (nearly equaling G. hispidus), with proportionally smaller 
pouches and hands, and weaker claws (these parts being as in G. hispidus}. 
Tail and feet clothed (as usual in the genus), not naked as in G. hispidus 
and G. tuza. 
HABITAT. Mexico. 
Description (No. 3523, Xalapa, De Oca, skin). The general appearance 
of this animal is so exactly that of an overgrown or overstuffed specimen of 
ordinary bursarius, that I shoujd be at a loss for terms referring to color to 
precisely characterize it. It is, nevertheless, entirely distinct from this or 
any other species. It shares, with G. castanops, the single median* furrow of 
the upper incisors, and some other points of form ; but it is much larger, and 
altogether of a different color. The excellently well-prepared and not over 
stuffed specimen here described is only equaled in a large series of G. bur 
sarius by a single much overstuffed example. The dimensions cannot be 
given with entire accuracy ; but the species probably averages, when full- 
*G. hispidus has been described as baving a single median furrow ; tbe emphasis here, however, ia 
upon " single," in antithesis to the double furrow of G. bursarius, without reference to exact position. G. 
tuza is said to have a "siugle" furrow; but the proper implication is merely obsoleteness of the fine 
inner second furrow usually seen. In G. mexicanus, as in G. castanops, the furrow is truly single and 
median; in G. hispidus, single and internal ; in G. tuza, apparently single and external. 
