3.8 4.8 .. 6.9 6.0 42588 KU, ? .. .. 4.9 .. 6.9 6.2 Notiosorex evotis, Mazatlán, Sinaloa Average 4 (♂) 17.68 4.05 5.37 8.68 7.60 6.58 Minimum 17.4 4.0 5.3 8.5 7.5 6.5 Maximum 17.9 4.1 5.4 8.8 7.7 6.7

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Average and extreme external measurements of the four males are as follows: total length, 93.2 (90-98); length of tail, 25.5 (23-27); length of hind foot, 11.9 (11-13); length of ear from notch, 7.7 (7-8); weight in grams, 5.4 (4.4-6.3). Cranial measurements are given in Table 1.

Notiosorex evotis was described by Coues (1877:652) on the basis of a single specimen, obtained at Mazatlán by Ferdinand Bischoff in 1868, that originally had at least the partial skull inside. Subsequently the skull was removed and evidently lost (Poole and Schantz, 1942:181). Coues named evotis as a species distinct from crawfordi (described by him in the same paper) on the basis of larger size, shorter tail, and alleged slight differences in color. He did not describe the skull, but did note that the dentition was "substantially the same as that of N. crawfordi." Evidently, the only other correctly identified specimen of evotis on record is an individual from Mazatlán in the British Museum, the skull of which was figured by Dobson (1890:pl. 23, fig. 20).

Merriam (1895:34) characterized evotis, known to him by only the holotype, as: "Similar to N. crawfordi, but slightly larger and darker." He did not examine the skull, which by that time had been "lost or mislaid." Merriam reduced evotis to subspecific status under crawfordi with the following remarks: "In the absence of sufficient material of N. evotis, it is impossible to determine its exact relations to crawfordi. Dobson did not recognize it as distinct, but figured its teeth under the name crawfordi [loc. cit., possibly a lapsus]. For the present it seems best to retain it as a subspecies."

Merriam's arrangement of evotis as a subspecies of crawfordi has been followed by subsequent workers, mostly, we suppose, because additional material of undoubted evotis has not until now been available. Comparisons of our four specimens with specimens (from Jalisco, Sinaloa and Tamaulipas) and published descriptions and measurements (see especially Hoffmeister and Goodpaster, 1954:46-47, 51) of crawfordi reveal that evotis has a longer body and hind foot than crawfordi but a relatively (sometimes actually) shorter tail and ear, and a distinctly larger, heavier skull (see Table 1). The upper parts of our specimens average pale brownish gray and are paler, not darker, than the upper parts of crawfordi. But, all of the latter were obtained in the warm months of the year except one November-taken individual from El Fuerte, Sinaloa, the dorsal pelage of which approaches in color that of the darkest of the evotis. The pelage of both kinds probably is paler in winter than in summer and may be indistinguishable in the same season. Ventrally, all four evotis are grayish white, faintly to moderately tinged with brownish buff.

Notiosorex evotis differs cranially from Notiosorex crawfordi as follows: larger (see measurements); mesopterygoid fossa squared rather than broadly U-shaped anteriorly; rounded process on maxillary at posterior border of infraorbital canal well developed (faint or lacking in crawfordi); occipital condyles smaller and, in lateral view, elevated above basal plane of skull; upper molars slightly more crowded in occlusal view. These differences, although admittedly slight, appear to be constant in the specimens we have seen, but ought to be used cautiously owing to the small samples studied.

Shrews of the genus Notiosorex have been reported twice previously from localities in west-central México, other than from Mazatlán, as follows: 21 mi. SW Guadalajara (remains from owl pellets) and 13 mi. S, 15 mi. W Guadalajara, Jalisco, by Twente and Baker (1951:120-121); and Cerrito Loco, 2 mi. E La Palma, Michoacán (remains from owl pellets), by Baker and Alcorn (1953:116). The remains were referred to evotis on geographic grounds in one instance and were so referred inferentially in the other. Examination of the specimens upon which these reports were based reveals that all are crawfordi on the basis of characters previously cited. As a result, N. evotis is known only from the type locality at Mazatlán, whereas N. crawfordi is widely distributed on the Mexican Plateau as far south as Jalisco and northern Michoacán, and occurs on the west side of the Sierra Occidental as far south as northern Sinaloa.

The two kinds obviously are closely related and intergradation eventually may be demonstrated between them. But, for the present, we adopt a conservative course and treat evotis as a full species owing to its distinctive features, restricted geographic distribution, and the lack of evidence of intergradation between it and crawfordi.

Balantiopteryx plicata pallida Burt.—Thirty-five specimens from two adjacent localities along the Río del Fuerte in northern Sinaloa, 3 mi. NE San Miguel, 300 ft. (84944-48) and 10 mi. NNE Los Mochis (60572-75, 60667-78, 60681-94), provide the first records of the subspecies from the state. Individuals from both localities were shot at dusk as they foraged among trees in the valley of the river. Fifteen of 18 females from 10 mi. NNE Los Mochis, collected on June 5, 6 and 7, 1955, were pregnant; each contained a single embryo, the embryos ranging from 7 to 15 mm. in crown-rump length. B. p. pallida previously has been reported from the southern parts of Baja California and Sonora.

Balantiopteryx plicata plicata Peters.—Specimens in the Museum of Natural History from the following localities, several of which are marginal, document better than previously has been done the distribution of this subspecies in Sinaloa: 32 mi. SSE Culiacán (60699); 10 mi. SE Escuinapa (68629); 17 mi. SSE Guamúchil (60576); 5 mi. NW Mazatlán (85537-61, 85901-04); 1 mi. SE Mazatlán, 10 ft. (39461-76); 1 mi. S Pericos (60697-98, 60700); ½ mi. E Piaxtla (60701); ½ mi. W Rosario, 100 ft. (39477-79); 5 mi. SSE Rosario (60702-03); 4 mi. N Terrero (60695-96).

Pregnant females, each with a single embryo, were recorded in 1954 from 4 mi. N Terrero, 2 (June 9), 1 mi. S Pericos, 2 (June 13), and 5 mi. SSE Rosario, 2 (June 20). None of 16 December-taken females from 5 mi. NW Mazatlán was pregnant.

The specimen from 17 mi. SSE Guamúchil, preserved in alcohol, is provisionally referred to B. p. plicata on geographic grounds inasmuch as