40 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
the same, and with nearly the same limits of variation that were found in the 
Carolina series (4.40 to 6.00), though none drop to 4.00, The same may be 
said of the ears, fore feet, head, nose to ear, and nose to eye. The case is 
different respecting the tail and hind feet, in which we get some new figures 
requiring attention, as the dimensions of these parts have entered into the 
specific diagnoses. 
For all the United States specimens, except three (Nos. 8820, 566, and 
8), both the absolute and relative length of the tail is almost exactly as in 
Carolina skins; if anything, the tail is rather shorter than longer. In none 
of the United States specimens do the feet differ appreciably from the Carolina 
figures. In No. 8, the tail first touches 4 inches; the tail of 8820 is a little 
longer (4.30); that of 566 (type of “berlandieri”) is still longer (4.60). But 
not one of these even equals, not to mention exceeding, the head and body, as 
alleged for “berlandieri”. In several Mexican skins, similarly, the tail sur- 
passes 4.00 (Nos. 9385, 9508, 9509, 9510); and in two of these (9509, 9510) 
it actually equals the trunk. These are the only instances of this occurrence 
in the whole series; and that they fall in the category of individual variations 
is proven by the following considerations :-—First, these specimens are associ- 
ated with others (Nos. 9534, 6995, 6996, 7210) positively identical in every 
respect, and in which the tails bear the ordinary positive and relative length 
of Carolina skins; secondly, the Texan and Mexican skins differ more znéer 
se in length of tail than they do from the Carolina ones; thirdly, we can 
form from our two tables the following graduated series of tails’ lengths: 
2.25, 2.40, 2.50, 2.70, 2.75, 3.00, 3.10, 3.20, 3.30, 3.40, 3.50, 3.60, 3.70, 3.75, 
3.90, 4.00, 4.30, 4.40, 4.60, 4.70, 5.00, 5.25! Where shall we make a break 
in this chain to establish specific difference upon length of tail? It is hard 
to admit a variation of two inches in the tail of an animal the tail of which only 
averages three inches long; but we do not see how to get around the figures. 
We found the feet of Carolina specimens to range from 1.00 to 1.30. 
Among the Southwestern United States and Mexican examples, we have a 
slight widening of the limits—from 0.97 to 1.37 and 1.40. The foot of 4927 
is indeed enormous, 0.10 longer than the maximum Carolina foot, and heavy 
in proportion; while that of 9384 is hardly less. But No. 9385 (a specimen 
that might have been twin-brother to 9384, the two are so absolutely alike in 
other respects) immediately sinks the figure to 1.80, which is at the Carolina 
extreme; and No. 4927 bis (taken along with 4927) has the foot within ordinary 
