I 78 Bulletin American Museum of Natural History. [Vol. XIV, 



POSTSCRIPT 



Since this paper was put in type I have received through the 

 kindness of Dr. C. Hart Merriam, Chief of the Biological Sur- 

 vey of the United States Department of Agriculture, five speci- 

 mens of Didelphis collected by Messrs. E. W. Nelson and E. A. 

 Goldman, at Chichenitza, Yucatan, and Apozote, Campeche, 

 during January and February, 1901, These specimens, with 

 others from Merida, Yucatan, indicate a form distinctly separable 

 from any heretofore recognized. It may be characterized as 

 follows : 



Didelphis yucatanensis, sp. nov. 



Type, No. 100299, Biol. Surv. Coll.. U. S. Nat. Mus., $ adult, Chichenitza, 

 Yucatan, Jan. 29, 1901 ; E. W. Nelson and E. A. Goldman. 



Nearest in size and external features to D. caucce^ but much smaller. Coloration 

 and character of pelage not especially distinctive. Dichromatic, both the black,, 

 and the gray phase being about equally represented . Nose and nails flesh color ; 

 ears, feet, and basal half to three-fourths of tail black. Size, very small, inter- 

 mediate between that of D. caucce and D. pernigra, and hence a pigmy in 

 comparison with D. richmondi and the various members of the D. marsnpialis 

 group, which widely separate it geographically from D. caucce, which latter is 

 also much larger than D, yucatanensis. 



External Measurements. 



