LEP0RIDJ5— LEPUS SYLVATICUS VAR. NUTTALLI. 331 



are scarcely smaller than those from Iowa or the Eastern States, while the 

 proportions seem to be absolutely the same. 



This form was formerly supposed to be much smaller than L. sylvaticus, 

 but the large number of specimens before me indicates but a slight average 

 difference in size, var. nuttalli being rather the smaller, with a very decided 

 decrease in size to the southward. Specimens from the northward have a 

 fuller and softer pelage and more heavily-clothed ears and feet than var. 

 sylvaticus anywhere presents. In those from along the eastern edge of the 

 plains, the tints are brighter than in those from further westward ; specimens 

 from along the Missouri, from about Fort Leavenworth to above Fort Randall, 

 being so nearly intermediate between the typical nuttalli and sylvaticus that 

 the majority of them may be as well referred to the one form as to the other, 

 while there may occur occasionally typical examples of each. The lightest 

 specimens appear to be those from Western Wyoming, Colorado, Nevada, and 

 Utah ; Arizona specimens passing gradually into variety arizonce. Winter 

 specimens are rather lighter than summer ones. In some of the former, the 

 subterminal zone of the hairs presents but a faint trace of yellowish, while the 

 sides and hinder part of the back are of a delicate gray, from the intimate 

 blending of the black and white hairs. Through the excessive paleness or 

 almost total obsolescence of the yellowish-brown tint so conspicuous in var. 

 sylvaticus, the black tips of the hairs are more conspicuous, standing out in 

 stronger relief against the nearly white ground-color, and thus sometimes 

 give the effect of a greater amount of blackness. 



The average length of the body in a series of nineteen specimens from 

 various localities is 13.75 inches, with the extremes ranging from 12.00 to 

 16.00 ; of hind foot, 3.41 inches, with the extremes ranging from 3.00 to 4.25. 

 The average length of fifteen specimens from the Atlantic slope is 15.35 ; 

 of twenty specimens from the vicinity of the Missouri River (from various 

 localities between Fort Randall and Fort Leavenworth), is 15.50. Variety 

 nuttalli hence averages about one and a half inches shorter than var. sylvati- 

 cus, or about 12 per cent, smaller. The measurements of the skulls indicate 

 about the same proportionate difference in size. 



There are in the collection a considerable number of specimens collected 

 in the vicinity of Brownsville and Matamoras, near the mouth of the Rio 

 Grande. These include Baird's types of his L. "bachmani" (= bachmani 

 Waterhouse), which I at first referred to variety nuttalli, but now believe to 



