492 U. Ss. P. R. R. EXP. AND SURVEYS—ZOOLOGY—GENERAL REPORT. 
of arched galleries of sticks and twigs, filled up with mule dung and moss, and from four to 
eight feet long, terminating usually in a bed of moss or hair under a rock. 
This spceies is readily distinguished from N. jloridana by its much smaller feet and rather 
more hairy tail, as well as by the much lighter color above and on the sides. The fur is longer, 
fuller and softer than in either NV. floridana or N. micropus. There is no indication of the slate 
gray of WN. micropus, and it has a more densely furred tail, which also appears longer. The 
feet, also, are even smaller than in NV. micropus. Skull broader than in N. floridana. 
Since preparing the preceding article, a large number of specimens has been received, which 
tend to establish the species more fully. Among them are several from the Colorado river, 
collected by Mr. Schott, and three from the Pecos, collected by Capt. Pope. These are generally 
similar, except that one (No. 1730) is of a light grayish slate color, lined with darker. This 
is lighter than as described in NV. micropus. I have not been able to examine the skulls, to see 
if they agree with the characteristics derived from the first specimens. 
A very good figure of this animal has been published in the Atlas of the Voyage of the Venus, 
taken from a specimen collected in Lower California by M. Neboux. This extends its distribu- 
tion from the Pecos river to the Gulf of California, and gives to it, compared with N. micro- 
pus, somewhat the same range as Spermophilus spilosoma, compared with S. mexicanus. 
Inst of specimens. 
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= Measurements. 
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289 |1674)...... Chihuahua City.... .ssj..cscccccesces -60/1.18) +85) .84 
SEIN a sel a wines Chevate springs, Sonora)......-.e.+008 SSL 17] tes} onselacec|enues tun eneven 
1033 = /2201)...... San Pedroriver, Sonora.|.....+s0++ 0.05 eleece +|«ees/eee-| Dr. Kennerly. 
ims |....| O | Colorado bottom, Cal,.} Mar. 31, 1855 |....-... ++ |1,33]....].+./1.00) A. Schott.... 
1329 2160) Q |........ GON cereaen Bee April 4, 1855 1.30/1.80] .98] .95|....do....eees 
1339 to i 
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1606 jowseleceees San Diego, California ..)......+0e+e008 56)1.18).. 1.05) 
71731 |....| @ | Pecos, New Mexico....| June 14, 1856 | Capt. J. Pope..... see /e.dO.ee oe] 8.00 |...|enee) enon! S| BR Be eee cs 
U7G2 Jrvns| QD Jevcvncceceercrennenncees | May 12, 1856 L40]|22-| case |osue| scenes aenenaee 
Es) | aseel hs e)e_| ssas5onc: ‘oceaccaco-e-t | June 5, 1856 1.33).. 70) .cosnsinn=e@abe 
| 
t Five young ones, belonging to 1329. 
NEOTOMA MICROPUS, Baird. 
Black Wood Rat. 
Neotoma micropus, Barrp, Pr. A. N. Se. Phila. VII, April, 1855, 333. 
Sr. Cu.—Above grayish slate, beneath with feet white. Feet small. Tail hardly two-thirds the length of body ; scantily 
haired. Feet entirely white. 
This species is about the size of the Florida rat, Neotoma jfloridana, or a little larger, and 
belongs to the same section of slender tailed species. The head is broad and pointed, the 
whiskers longer than the head, mixed black and gray. The ears are very large, broad and 
