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NORTH AMERICAN FAUNA. 



MYOTIS YUMANENSIS (H. Allen). 

 1864. T'e,q)e)'liHo 1/ inn an ens is H. Alleu, Mouogr. N. Am. Bats, p. 5S. 



186G. Vcspertilio macroj>HS H. Allen, Proc. Acad. Nat. Sci. Pliila., p. 288, (neo Gould, 

 1854). 



1898. Ves2)t'rtirio nitidu.'i (pedoruorphic variety) H. Allen, Monogr. Bats N. Am., 

 pp. 72. 73. 



1893. VespertiUo albescens H. Allen, Monogr. Bats N. Am., p. 87, (part, nec Geoff., 

 1805). 



1893. VesperiUio nitidus macropus H. Allen, Mouogr. Bats N. Am., p. 100. 



Tyj^e locality. — Old Fort Yuma, California. 



Geograi^hic distribution. — Austral zones and lower edge of Transi- 

 tion zone from tlie southwestern United States to San Luis Potosi and 

 jMicboacan, Mexico. 



General characters. — Size small; length 74:-88; forearm 32-37 ; calcar 

 distinct, considerably longer than free border of interfemoral mem- 

 brane, terminating in a well-marked lobule; free border of uroi)atagium 

 naked: ears moderate; wings from base of toes, but on account of 

 extent of web between toes apparently from side of metatarsus; feet 

 very large and strong as compared with other small American species. 



Uars. — The ears (PI. I, tig. 2) are moderately long; laid forward they 

 reach just beyond the tip of the nose. The anterior border is straight 

 for a short distance at base, then strongly convex, and finally straight or 

 even slightly concave just below ti]}. The tip is narrow and abruptly 

 rounded oif. The i)osterior border is concave from the tip to the 

 widest ])art of the auricle, just below mid height, then strongly convex 

 to basal notch, which isolates a well-marked rounded lobe. 



Tragus slender, acutely pointed. Anterior border slightly concave 

 at base, then straight or very faintly concave to tip. Posterior border 

 crenulate, straight or slightly concave from tip to broadest point at 

 about lower third. A very large lobe at base; this lobe so large that 

 the greatest breadth of the tragus is often through it. 



Membranes. — The membranes, especially the uropatagium, are, for so 

 small a bat, thick and leathery. The interfemoral membrane (PI. II, 

 fig. 2) is furred at the base, both dorsally and ventrally,but otherwise is 

 naked except for a sprinkling of short hairs along the veins. Wings 

 from base of toes, but on account of the consx)icuous webbing of 

 the latter the membrane ai^i^ears to be attached to the side of the 

 metatarsus. 



Feet. — The feet (PI. II, fig. 2) are, for so small a bat, very large, broad, 

 and strong, more than half as long as the short tibiae, the whole leg 

 and foot suggesting a small Nycticeius rather than a Myotis. Toes 

 (without claws) as long as sole, united by membrane at base to distal 

 fourth of proximal phalanges. Calcar strong and distinct, much longer 

 than free border of uropatagium, usually terminating in a distinct 

 lobule. Keel on x^osterior edge very slightly developed. 



Fur and color. — The fur shows no peculiarities in distribution. On 

 the middle of the back it averages about 6 mm. in length. 



