44 Fretp Museum or NaAturRAL History — Zo6éxocy, Vor. 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, 1,060; tail vertebree 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 premaxille 
to front of pm * 55.5, 56.1, (57.4); least breadth of basioccipital 16.6, 
16.1, (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 * 56.2, 56.3, (52.1); 
pm 9.5x6, 9.9xX 7.6, (7.6x 6.8); M * 12.7x 12.4, 12.1X 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, 
