imen is morphologically as well as
geographically intermediate between _S. f. cognatus_ and _S. robustus_.
This morphological intermediacy is illustrated by certain of the
following cranial measurements of three adult females: No. 108695
(_robustus_), Chisos Mts.; No. 658 from the Guadalupe Mts.; and No.
128651, NE slope Capitan Mts. Basilar length, 59.2, 54.2, 54.4; length
of nasals, 33.9, 31.1, 32.2; breadth of rostrum above premolars, 19.3,
17.5, 17.0; depth of rostrum in front of premolars, 15.8, 14.8, 14.0;
interorbital breadth, 20.4, 19.1, 19.7; parietal breadth, 27.2, 27.1,
26.5; diameter of bulla, 13.3, 12.2, 10.7. Considering the intermediate
nature of specimen No. 648, and the kind and amount of difference
between _Sylvilagus floridanus cognatus_ and _S. robustus_, it seems
appropriate to us to use the name-combination _Sylvilagus floridanus
robustus_.

Actual intergradation, in the sense of interbreeding between individuals
of a continuously distributed population of animals, probably does not
occur regularly between _S. f. cognatus_ and _S. f. robustus_ nor
between several populations within either one of these subspecies; in
south-central Arizona and western Texas the animals are said to occur
only in the higher parts of the mountains. Consequently a given
population is separated from another by low-lying territory inhospitable
to the species _Sylvilagus floridanus_. This low-lying territory is
inhabited by another species, _Sylvilagus audubonii_. More intensive
collecting in the region concerned may, however, show a continuous
distribution of the species _Sylvilagus floridanus_ in several areas
where it seems now to have an interrupted distribution.

Sylvilagus audubonii neomexicanus Nelson

1907. _Sylvilagus audubonii neomexicanus_ Nelson, Proc. Biol. Soc.
Washington, 20:83, July 22.

Nelson (N. Amer. Fauna, 29:230, August 31, 1909) listed under
_Sylvilagus audubonii cedrophilus_ Nelson an adult female, skin with
skull (U.S. Nat. Mus., Biol. Surv. Coll., No. 108698) from fifteen miles
south of Alpine, Texas. Nelson (_loc. cit._) remarked that the
"bleached" color of the back and the great lateral breadth of the
tympanic bullae of No. 108698 were peculiarities not possessed by any
other specimen examined. Geographically, the locality of capture is far
south of other known occurrences of _S. a. cedrophilus_ and
approximately on the boundary separating the range of _S. a. minor_ from
that of