NATURAL SCIENCES OF PHILADELPHIA. 



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evident, and in short, I find no color differences not explicable 

 upon consideration of the comparative state of the two specimens. 

 We may therefore turn to the matter of size and proportions. 

 Prof. Baird says, " tail rather shorter than head and body," giving 

 the length of the former as 2.67 -f, and of the latter as 3.00 ; 

 whereas my animal is but 2.50 long, and has a tail of 3.20. But 

 the decided discrepancies in these statements and measurements 

 are readily reconciled upon the simple consideration that the tail 

 is defective and the body over-stuffed in the type of monlicola. 

 This brings about an agreement further borne out by the other 

 measurements. In the following table, the first line of measure- 

 ments are copied from Baird ; the other is taken from the Fort 

 Crook specimen, upon which this article is based, before skinning 

 out of alcohol. 



Measurements. 



The principal discrepancy being explicable as above, there is 

 nothing whatever in the foregoing table incompatible with specific 

 identity. Moreover, it so happens that the left ear of the type is 

 in sufficiently good preservation to enable me to clearly recognize 

 the peculiar conformation which distinguishes the present species 

 from the others. 



To this same species I am also inclined to refer two specimens 

 collected by Mr. H. W. Henshaw on Otter Creek, in Utah. These 

 are apparently 3 r oung animals, but, as they are not accompanied 

 with the skulls, the fact cannot be determined. The tail of each 

 has been skinned, and is now so shrivelled that nothing can be 

 predicated as to its length, either relative or absolute. The spe- 

 cimens are quite small; they have been over-stuffed, measuring 

 now about 2^ inches, but were probably not much if any over 2, 

 with a hind foot of 0.80; in fact they might be taken at first sight 

 for a Cricetodijms. But the soles are naked along a narrow strip 



