(—), 19.0 (20.8); mastoidal breadth, 13.9 (14.4), 13.9 (14.8); greatest breadth of rostrum, 7.2 (7.3), 7.8 (7.2); length of nasals, 14.6 (14.1), 13.4 (14.2); crown length of upper molar teeth, 6.3 (6.1), 6.3 (5.9).

Specimens examined.—Two from the type locality.

Lepus californicus curti new subspecies

Black-tailed Jack Rabbit

Type.—Female, adult, skull and skin, No. 35470, Mus. Nat. Hist., Univ. Kansas; from island, 88 miles south and 10 miles west of Matamoros, Tamaulipas, Mexico; obtained 19 March 1950 by E.R. Hall; original No. 6783.

Range.—Islands along coast of Tamaulipas, Mexico.

Diagnosis.—Color pale; size small; ears short; tympanic bullae small.

Comparisons.—From Lepus californicus merriami Mearns (specimens from Fort Clark, Brownsville and intermediate localities), L. c. curti differs in paler color, lesser size except ear that is of almost same length and except interorbital breadth that is approximately same in the two subspecies; tympanic bullae notably smaller. From Lepus californicus altamirae Nelson, L. c. curti differs in having the black patch on the nape less definitely divided by a median, longitudinal band of buffy color, and lesser size. Exception is to be made for the ear and tympanic bullae, which are of approximately the same size in the two subspecies.

Remarks.—The subspecific part of the name Lepus californicus curti is proposed in honor of Dr. Curt von Wedel who shared the pleasure of collecting on the islands where this handsome hare lives.

The specimens of L. c. curti are all females, which, in the genus Lepus, average larger than the males. Comparison of the measurements recorded below with those in the account by Nelson (N. Amer. Fauna, 29:129, 1909) may not reveal the full measure of difference in size between L. c. curti and other subspecies because Nelson (op. cit.) pooled males and females in obtaining the average measurements that he records. For example, he used three males and two females of Lepus altamirae in obtaining an average (op. cit.:117). The specimens of L. c. curti here recorded are thought to be of full size inasmuch as the degree of fusion of bones in the skull, and the density of the cranial bones indicate full adulthood for each specimen. Reproductive-wise, there is no question as to adulthood; each of the four females was pregnant. One specimen had two embryos (each 30 millimeters long in crown-rump measurement) and each of the other specimens contained one embryo. These three embryos were 55, 60, and 105 mm. long.

Three of our specimens, including the holotype, were obtained north of the eighth pass and the other specimen, No. 35473, was obtained a few hundred yards south of the pass. Because the part of the barrier beach south of the pass was connected to the mainland, it is likely that the newly named subspecies occurs also on the adjacent mainland; however, we have examined no specimens of Lepus californicus from the opposite mainland except from Matamoros, ninety miles to the north, and from Altamira, approximately one hundred and fifty miles south of our collecting locality. A specimen from Matamoros, Tamaulipas, and several from Brownsville, Texas, in size of auditory bullae, larger overall size and darker color clearly are L. c. merriami and not L. c. curti.

The small tympanic bullae of the specimens from Padre Island were commented upon by Nelson (op. cit.:149) who found smallness of bullae to characterize many of the specimens from the eastern part of the geographic range of L. c. merriami. In the northeastern part of the geographic range of L. c. merriami, as Nelson pointed out, the small size of the tympanic bullae was one of several evidences of intergradation there with Lepus californicus melanotis, the subspecies next adjacent to the north. In the light of present information, it seems that the smallness of the tympanic bullae in the specimens (3) from Padre Island may be an independent development—an adaptation to environmental conditions that reaches its fullest development on the same chain of islands eighty-odd miles southward of Matamoros. The specimens from Padre Island, although possessing small bullae, in other features, for example, larger size of other parts, are merriami.

The four specimens of L. c. curti are in worn winter pelage and the new pelage is coming in on the thighs. Most of the specimens (6) of the L. c. altamirae are in the same condition of pelage. In color and color pattern, the two subspecies are, to me, indistinguishable except that the black patch on the nape is less widely and less definitely separated into two parts by a median, longitudinal, band of buffy color.

Lepus californicus altamirae was named by Nelson (Proc. Biol. Soc. Washington, 17:109, May 18, 1904) as a black-tailed jack rabbit, Lepus merriami altamirae, but was later transferred by Nelson (N. Amer. Fauna, 29:124, 1909) to the white-sided section of the genus and arranged as a full species, Lepus altamirae. In making this transfer, Nelson (op. cit.:125) wrote that in "This well marked species ... the lack of a black patch on the posterior half of the ear at the tip and the white flanks (somewhat obscured in some of the original specimens) are strong characters which place it in the callotis group." "Posterior half of ears white without any trace of black at tip", was the way Nelson (op. cit.:124) described the ears in L. altamirae. My examination of the original series including the type, reveals that the ears do have some black at the tip of the posterior half in three of the specimens, some brown in one other specimen, and only a dusky tinge in two others. In the four specimens of L. c. curti the tip of the ear is faintly brownish in one animal and dusky in three. The extent of the white flanks seems to be identical in the two series. Fortunately they are in the same pelage and same stage of molt on the hind legs. The one difference that I can detect is in the coloration of the nape. In each of the specimens of L. altamirae the coloration is as described by Nelson (op. cit.:124): "nape with two lateral black bands extending back from base of ears, and separated by a median band of buffy." In L. c. curti the nape is all black in one specimen and the median band of buffy is present in the other three but is narrower and more dusky than in L. altamirae. Since the characters (color of tip of ear and extent of white on the flank) relied upon by Nelson for placing L. altamirae in the callotis group are duplicated in the californicus group, in L. c. curti, there is reason for questioning whether altamirae is correctly placed, taxonomically, in the L. callotis group.

Cursory examination of skulls of the callotis group and the californicus group indicates that the prepalatal spine (the part of the palate which extends anteriorly toward the vomer) is longer in L. californicus than in L. callotis, L. gaillardi and L. alleni. In this feature, L. altamirae agrees with Lepus californicus and differs from members of the Lepus callotis group. Furthermore, the newly named L. c. curti, in color of ear and color of nape, is intermediate between L. altamirae and L. c. merriami. Consequently, Lepus merriami altamirae Nelson, it seems, should stand as Lepus californicus altamirae.

Mention should be made here of the view of Shamel (Proc. Biol. Soc. Washington,