1907. _Sylvilagus floridanus similis_ Nelson, Proc. Biol. Soc.
Washington, 20:82, July 22.
Some confusion has existed concerning the subspecific identity of the
Florida cottontail in Nebraska because of the way in which Nelson
recorded specimens in his "The Rabbits of North America" (N. Amer.
Fauna, 29:fig. 11, and pp. 169-174, August 31, 1909). He (_op.
cit._:174) listed the following specimens under the western subspecies,
_S. f. similis_: Two topotypes (Nos. 87784 and 18738/25532) and of
course the type; the specimen (No. 116288) from the Snake River [= Snake
Creek of maps], 11 mi. NW Kennedy; two from Neligh (126074 and 151438);
and one (probably 18680/25410) from Kennedy. But, he listed (_op.
cit._:172) under _S. f. mearnsi_, the eastern subspecies, a specimen
(10721) from Brownlee, and two from Kennedy. One of the two from Kennedy
probably was the one that is recorded in the files of the U.S. Fish and
Wildlife Service as "identified by Cary. spec. in Univ. Nebraska". The
other, or third, specimen from Kennedy, we judge, did not exist at all
but was recorded by Nelson because a card in the reference file, under
Kennedy, Nebraska, in addition to No. 18680/25410, carried a second
entry, a number 3471X. The latter is the X-catalogue number of specimen
No. 116288 from the Snake River! The X-catalogue is used in place of a
field catalogue for specimens sent to the mammal collection of the
United States Fish and Wildlife Service, by persons who do not keep
regular field numbers of their own. It seems that Nelson prepared (or
had prepared) his lists of specimens, at least in part, from cards
rather than from the labels on the specimens themselves. Some further
confusion as to names that Nelson intended to apply to cottontails in
Nebraska resulted from the fact that his map (_op. cit._:fig. 11)
indicated that the localities mentioned above for _S. f. mearnsi_ were
within the geographic range of _S. f. similis_.
Our comparison of each of the Nebraskan specimens with specimens of _S.
f. mearnsi_ in comparable pelage from Iowa and with the type and
topotypes of _S. f. similis_ reveals that each of the specimens of which
catalogue numbers are given above is clearly referable to _Sylvilagus
floridanus similis_.
Because some mammalogists have suspected that intergradation between
_Sylvilagus floridanus similis_ and _Sylvilagus nuttallii grangeri_
occurs along the eastern base of the Rocky Mountains, we have examined
specimens which may throw light on this matter.
From _S. f. similis_ (holotype and three topotypes), _S. n. grangeri_
(eight practical topotypes from Redfern, South Dakota) differ as
follows: Throat patch darker; hind foot shorter; ear (dry) from notch
longer; rostrum narrower; posterior extension of supraorbital process
enclosing a longer and wider space between it and the braincase;
superior border of premaxilla straight in profile instead of convex
dorsally; tympanic bullae more inflated; external auditory meatus larger
(diameter of the meatus more, instead of less, than crown length of
upper molars); posterior border of palate without, instead of with,
spine.
Specimens of the two species from places as near each other as extreme
southeastern Montana (_S. f. similis_ from Boxelder Creek, Capitol and
the Little Missouri River) and Devils Tower, Wyoming (_S. n. grangeri_),
seem not to differ in the length of the hind foot and the ear and in the
color of the spot on the chest. Also, the presence or absence of the
spine on the posterior margin of the palate is subject to individual
variation in these specimens but the other cranial differences,
mentioned above, still are apparent. These same cranial differences are
readily apparent between specimens of the two species taken only five
miles apart in eastern Wyoming (for the precise localities, see the
following paragraph). It is concluded, therefore, that _S. f. similis_
and _S. n. grangeri_ do not inter-grade along the eastern base of the
Rocky Mountains.
Data on specimens from Laramie County in eastern Wyoming show that _S.
f. similis_ is a heavier animal than _S. n. grangeri_ and also that
_similis_ molts earlier. For example, an adult female (K.U. No. 15936)
taken on July 13, 1945, three miles east of Horse Creek P.O., 6400 ft.,
weighed 1374 grams and is in fresh pelage, whereas an adult female of
_S. n. grangeri_ (K.U. No. 15935), taken on July 17, 1945, two miles
west of Horse Creek P.O., 6600 ft., weighed only 1149 grams, and still
has some of the worn winter pelage on the upper parts.