Vol. XXVI, pp. 175-176 August 8, 1913 



PROCEEDINGS 



OF 111 I 



BIOLOGICAL SOCIETY OF WASHINGTON 



TWO NEW MOUSE OPOSSUMS FROM YUCATAN. 

 BY WILFRED II. OSGOOD. 



Prof. Geo. F. Gaumer, who is so well known in connection 

 with the natural history of Yucatan, has recently presented 

 several interesting mouse opossums to the Field Museum of 

 Natural History. As suspected by Prof. Gaumer, they prove 

 to represent undescribed forms and are therefore named below, 

 one of them fittingly being dedicated to its discoverer. Spanish 

 descriptions of the same species will appear in Prof. Gaumer's 

 work on the mammals of Yucatan soon to be published by the 

 Department of Biological Survey of Mexico. 



Marmosa gaumeri sp. nov. 



Type, from Yaxcaba, southwest of Chichen Itza, Yucatan. Mexico. No. 

 19,0!).l Field Museum of Natural History. Collected Nov., 1912, by G. F. 

 Gaumer. 



Characters. — Similar in general to Marmosa canescens of the Tehuan- 

 tepec region, but decidedly smaller; coloration of upper parts suffused 

 with fawn rather than liutl'; under parts pale creamy instead of buff. 

 Upper parts dull brownish fawn finely and nearly uniformly mixed with 

 dusky producing a general effect which approaches drab or broccoli 

 brown; body color extending down outer sides of fore and hind legs 

 nearly or quite to carpal and tarsal joints: feet creamy white; forehead 

 and nose considerably paler than hack; blackish brown eye-ring well 

 developed but not reaching quite to the base of the whiskers anteriorly 

 nor to the ear posteriorly; cheeks, inner sides of legs, and entire under 

 parts pale creamy from the roots of the hairs; tail dull brownish drab 

 above, paler below. 



Skull much smaller than that of M. canescens; braincase small and 

 narrow; nasals short and narrow, practically without any posterior 

 expansion; postorbital processes and supraorbital shelf highly developed 

 between marked anterior and posterior interorbital constrictions. 



Measurements. — Type and additional specimen from Izamal, Yucatan, 



15— Proc. Biol. Soc. Wash., Vol. XXVI, 1913. (175) 



