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DESCRIPTION OF A NEW SPECIES OF CHIPMUNK FROM CALIFORNIA (Tamias macrorhabdotes sp. nov.).
BY DR. C. HART MERRIAM.
(Read December 26, 1885.)
I have recently secured, from the Sierra Nevada mountains of central California, a series of Chipmunks or Ground Squirrels which differ markedly from any known species. In size they closely approach typical examples of Tamias asiaticus townsendi ; and in coloration they are in some respects intermediate between vars. townsendi and borealis, while in other respects they are peculiar. They may be distinguished at a glance from all other described forms by the great length of the ear, the clearness and sharpness of definition of the light stripe which occupies its posterior half, and by the large size and whiteness of the spot behind its base. Tamias macrorhabdotes * sp. nov. LONG-EARED CHIPMUNK.
DIAGNOSIS.-Ears exceedingly long, measuring from 16 to 17 mm. in height from the occiput (average of ten, 16.20 mm.). Crown grizzled grayish-brown, more or less mixed with rusty; convex surface of ears sharply bicolor vertically, anterior half sooty-brown, with a slight admixture of rusty near the anterior margin, posterior half ashy-white in striking contrast; a large white spot (nearly as large as the ear itself) on each side of the neck just behind the ear and continuous with its ashy-white posterior half and with the white cheek-stripe under the eye, and almost continuous posteriorly with the external lateral white
• Macro-rhabd-ótes: plazpós, long; pá3ôvs, stripe; ós, wzós, ear,-in allusion to the long, striped ear, which is diagnostic of the species.
stripe ; five dark dorsal stripes (outer often indistinct), rusty umber to sepia brown; the two outer of each side separated by a grayish-white stripe which is almost continuous anteriorly with the white blotch behind the ear; the median and inner of each side separated by a grayish stripe more or less obscured with rusty ; rump grizzled gray sometimes tinged with brownish ; sides pale fulvous to deep rusty fulvous, the color extending well
up on the neck, but never back over the hips; under parts white or soiled white; tail above sub-terete, almost black, with hoary tips to the hairs and with more or less hazel showing through ; tail below distichous, mesially bright hazel, heavily bordered with black and edged with hoary. The facial stripes are highly developed and are five in number, three rusty umber and two white, as follows: A narrow white stripe runs from the tip of the nose to the anterior base of the ear, passing over the eye; it is bordered above by a stripe of rusty umber (which is broadest and darkest from the eye to the ear), and below by another of the same color which passes through the eye and terminates at the meatus; below this is a second white stripe, broader than the first, which runs just below the eye and thence backward under the root of the ear, where it bends upward and backward, becom
ing continuous with the white spot behind the ear; below this still is another rusty umber stripe which ends against the white just back of the ear.
MEASUREMENTS.–The twelve specimens before me are all skins, but they are well prepared and afford measurements which may be regarded as approximately correct. The length of head and body varies from 125 to 140 mm. and the tail with hairs from 105 to 130 mm. The hind foot with claw averages between 34 and 35 mm.
CRANIAL CHARACTERS.-The nasal bones are both relatively and absolutely longer in macrorhabdotes than in its nearest ally, townsendi, notwithstanding the fact that the latter is the larger animal. The longest nasal in the four skulls of townsendi before me measures 11.00 mm., while the smallest of five adult macrorhabdotes measures 12.60 mm. and the largest 13.20 mm.
The nasals usually project backward in macrorhabdotes beyond the line of the fronto-premaxillary suture, while in townsendi they generally end flush with the suture. Their ratio to the basilar length in townsendi is 35.73 mm. (average of two), against 44.54 in macrorhabdotes (average of five fairly adult specimens). In addition to their shortness, the nasal bones in townsendi average a little broader, particularly behind ; thus the average width (at the fronto-premaxillary suture) of four specimens of townsendi is 3.27 mm., while the average of eight specimens of macrorhabdotes is 2.85 mm. Hence the average of the ratios of the posterior breadth of the nasal bones to their length in nine skulls of macrorhabdotes is 22.97, while in four skulls of townsendi it
Interorbitally, the frontal bone averages somewhat broader in macrorhabdotes than in townsendi. The palate is longer in the latter. The average ratio of the length of the palate to the basilar length in eight specimens of macrorhabdotes is 53.96, while in two specimens of torensendi it is 56.80.
The parietal and supra-occipital bones co-ossify so early in life that in the adults it is generally impossible to detect the suture between them ; hence they are here measured together. They are very much shorter in macrorhabdotes than in townsendi. measuring from 10.60 to 11.oo mm. (four-tenths of a millimetre covering the limits of variation in nine specimens); while in townsendi two specimens measure respectively 13.50 and 13.00
The average of the ratios of the length of the parietals and supra-occipital, thus united, to the basilar length in eight skulls of macrorhabdotes is 37.87; in two of townsendi it is 45.77.
The first upper premolar is decidedly smaller in macrorhabdotes than in townsendi; it has evidently ceased to be functional and is fast becoming obsolete-one of many characters pointing to the higher differentiation of the new species.
The pretty little Striped Squirrel which forms the subject of the present paper is one of peculiar interest. It is surprising that an animal of its size and diurnal habits, and one which differs so markedly from even its nearest relative, should have escaped so long the notice of the many naturalists and collectors who have traversed the region. The most natural explanation is that the Long-Eared Chipmunk is an exceedingly local species, restricted in its range by certain physiographical conditions of which we are at present ignorant-conditions which were influential, doubtless, in bringing about the modifications which distinguish it from its congeners and mark it as one of the most highly specialized of the genus Tamias. That this genus is peculiarly susceptible to environmental influences is amply attested by the number and perplexing characteristics of the incipient species already known from the United States.
The specimens of this new species were collected by C. A. Allen, of Nicasio, California, and the accompanying figure was drawn by Ernest E. T. Seton.
ON A NEW METHOD OF PRODUCING IMMUNITY
FROM CONTAGIOUS DISEASES.
By D. E. Salmon, D. V. M., AND THEOBALD Smith, M. D.
(Read February 20, 1886.)
More than four years ago * one of us, in the study of the subject of insusceptibility to contagious diseases, reached the conclusion that, in those diseases in which one attack protects from the effects of the contagion in the future, the germs of such maladies were only able to multiply in the body of the individual attacked because of a poisonous principle or substance which was produced during the multiplication of those germs. And also that, after being exposed for a certain time to the influence of this poison, the animal bioplasm was no longer sufficiently affected by it to produce that profound depression and modification of the vital activity which alone allowed the growth of the pathogenic germs and the consequent development of the processes of disease. After several series of experiments, made at that time with only negative results, it became necessary to suspend these investigations until points connected with them, and which were then obscure, should be cleared up, and until it should become possible to repeat the experiments under more favorable conditions. Our expectations in regard to this important subject have at last been realized by the results of experiments recently made in the laboratory of the Bureau of Animal Industry.
The bacterium, which we have lately discovered and which we believe to be the cause of swine plague, is killed in liquid cultures by an exposure to 58° C. for about ten minutes.
This method of destroying the bacterium in liquid cultures was resorted to in studying the effects on pigeons of the chemical
* Department of Agriculture, Annual Report, 1881-2, pp. 290-295.