In a small collection of mammals recently sent by Dr. G.F. Gaumer from Izamal, Yucatan, to this Museum for identification, is a single specimen of a species of Adelonycteris, which appears to be undescribed. It may be called ADELONYCTERIS GAUMERI, sp. nov.
Above dark brown, with an olivaceous wash, the fur being uniform dark brown to the base tipped with a slight tinge of olivaceous, the extreme tip slightly grayish in certain lights; below much lighter, the fur being dark brown basally and broadly tipped with pale buffy gray; ears and membranes black, naked, and with no trace of a whitish border. Ears of medium size, rather thin, evenly convex on the front border, slightly hollowed on the posterior border below the rounded posteriorly directed tip; tragus long and rather narrow, pointed, equal to half the height of the ear. Face semi-nude, about as in A. fusca.