44 FIELD MUSEUM or NATURAL HISTORY ZOOLOGY, VOL. X. 



peculiarities; color paler and more grayish; cheek teeth 10 to 15 per 

 cent larger than in M. americana; anterior half of parieto-squamosal 

 suture abruptly deflected downward; basioccipital broad. General 

 color of upper parts grizzled cinnamon gradually becoming paler on 

 the sides where the punctulated effect is diminished and along the not 

 very sharp demarcation between upper and under parts where the 

 color becomes pale fawn or nearly ecru drab ; top and sides of neck and 

 sides of head and face brownish drab gray in considerable contrast 

 to general body color; chin and upper throat buffy white becoming 

 pale drab gray or ecru drab on lower throat and chest; belly buffy white, 

 this continued about half way down the inner sides of the legs; front 

 of forelegs deep brownish fawn merging into cinnamon and ochraceous 

 buff on the sides and about the hoofs; hind legs below the hock pale 

 drab all around, slightly darker in front; a white spot at tarsal gland; 

 tail white below, pale cinnamon above, the hairs drabbish at bases; 

 ears drabbish gray, the outside hairy at base and laterally but naked 

 or nearly so in middle, inside and anterior edges with long white hairs ; 

 a prominent white spot on each side of the rhinarium and thence bor- 

 dering the upper lips ; a white spot also above each eye ; ocular and post- 

 narial areas rather indefinitely cinnamomeous in contrast to more 

 grayish surrounding parts. 



Measurements. Type and adult female, respectively: Total length 

 1,090, i, 060; tail vertebrae 105, 115; hind foot 278, 280; circumference 

 of chest 600, 560; neck 240, 218; shoulder to hip 550, 570; height at 

 shoulder 545, 587. Skulls of type, one adult female from Empalado 

 Savannas, and one adult female M. americana from British Guiana,* 

 respectively: Greatest length 189, 185, (183); zygomatic breadth 80.6, 

 81.8, (76.3); greatest length of nasals 50.6, 59, (51.5); tip of premaxillas 

 to front of pm 1 55.5, 56.1, (57.4); least breadth of basioccipital 16.6, 

 1 6. i, (14.5); greatest depth of squamosal (from top of meatus) 25, 25.5, 

 (18.4); breadth of braincase 57.4, 55, (54.4); maxillary toothrow 61.5, 

 58.8, (51.5); breadth between outer sides of M 2 56.2, 56.3, (52.1); 

 pm 1 9.5 x 6, 9.9 x 7.6, (7.6 x 6.8); M 2 12.7 x 12.4, 12.1 x 12.2, (10.2 

 x 10.8). 



Remarks. Although there is considerable color difference, perhaps 

 the principal character distinguishing this form from typical americana 

 is the large size of the cheek teeth. To represent americana, one skin 

 and two skulls from the vicinity of Georgetown, British Guiana have 

 been available. Four specimens of the new form were taken by our 

 party: The type, an adult male; a slightly younger female which was 



* Measurements of M. americana in parentheses. 



