1906]. Allen, Mammals from Western Mexico. ' 195 



Measurements: An adult female, total length, 247; head and 

 body, 114; tail, 133; hind foot, 18; ear from notch, 22 mm. Two 

 adult males average, total length, 269; head and body, 127; tail, 142; 

 hind foot, 19 . 8; ear, 23. 



2. Didelphis mesamericana mesamericana (Okeri). 



Thirty-six skins and skulls, and 8 additional skulls, all from 

 Escuinapa, Jan. i-Feb. 2 (adults), June 26, July 5 (2 nurslings). 

 The series includes 15 adult males, n adult females, 3 young adults, 

 and 7 young apparently only a few weeks old (length of head and 

 body, 140-160 mm.). Of the adults 16 represent the black phase, 

 and 12 the gray phase, divided about equally as to sex, while the 

 8 young ones are all of the black type. The series, excluding the 

 nurslings, consists almost wholly of middle-aged adults, with a few 

 very old specimens and a few in which the dentition is not quite 

 mature. 



The measurements of this series, both external and cranial, fall 

 considerably below those of specimens from central and eastern 

 Mexico (D. mesamericana tabasensis), but agree in this respect with 

 specimens from Jalisco and Colima. 



Twelve adult males give the following: Total length, 805 (767- 

 845); head and body, 418 (394-445); tail vertebrae, 387 (373-406); 

 hind foot without claws, 56.5 (54-60); ear from notch, 51.3 (45-54). 

 Skulls of same: Total length, 112 (106-119); zygomatic breadth, 



53-5 (49-55)- 



Nine females: Total length, 747 (711-788); head and body, 376 

 (35 6 -394); tail vertebrae, 341 (328-390); hindfoot, 52 (48-56); ear, 50 

 (48-52). Skulls: total length, 100.6 (93-110); zygomatic breadth, 47 

 (42-52). 



A similar series of specimens from the State of Jalisco give practi- 

 cally the same measurements, the average total length of the skull 

 being exactly the same, and the external measurements average 

 practically the same, while a similar number of specimens from 

 the States of Vera Cruz, Tabasco, and Chiapas are much larger, as 

 follows: Total length (n males), 887; head and body 468; tail vert- 

 ebrae, 415; total length of skull, 121; zygomatic breadth, 61.5: 9 

 females, total length, 798; head and body, 412; tail vertebrae, 387; 

 total length of skull, 104; zygomatic breadth, 51. The difference 

 in total length is 82 mm. in the males and 51 in the females, and in 

 total length of skull in the males, 9 mm., and in zygomatic breadth, 

 8 mm., with corresponding differences in the females. 



