142 Proceedings of the Biological Societi/ of IJ'^ashwgton. 
31.9; zygomatic breadth, 64.1; l)readtli of braincase, 54.8; maxillary 
molar-premolar row, 25.4 ; combined width middle upper incii^ors, 10.4 ; 
mandihle, 63.4; mandibular molar-premolar row, 27.2. 
Remarks. —Of late years the spider moidveysof (Guatemala and .southern 
Mexico have been cond)ined by authors a.s a single variable si)ecies, 
under the name vellerosus or pan. The excellent series in the United 
States National iMuseum collection ju'oves, it would .'^eem, that they an' 
really distinct, and certainly much less varial)le than has been supposed. 
Great confusion has arisen from the u.se of specimens, in lairopean and 
American iMuseums, with imperfect data. Three tine adult specimens 
from Guatemala and a large series from various points in southern 
Mexico (including the specimens in the Biological Survey' collection) have 
been compared, and the animals from the two regions are so difterent 
that it seems improbable that they are onl^^ geogra])hic races of a single 
species. The Guatemalan AteJes pan is a large, long-haired, blackish 
monkey, distinctly of only two colors above, the head and fore parts of 
body black, the rump and lower back brownish. The Mexican form is 
distinctly tricolor above, head black, fore jiarts of body brown, lower 
back and rump sharply saddled with yellowish-bulT. There are also 
numerous constant minor differences as described above. Doctor Elliot 
has shown* that all the names, with the exception of pan, which have 
been used for the spider monkeys of this region, reallj^ fo South 
American forms. 
Procyon lotor crassidens subsp. nov. 
Type from Talamanca, Costa Rica. Adult [cJ'j, skin and skull (basal 
and nasal sutures not closed), U. S. National 5Inseum No. tIiIt- Col¬ 
lected by William 51. Gabb. Grig. No. 14. 
General characters. —Like Procyon lotor hernandezii oi southern 5Iexico 
and Guatemala, but with decidedly larger molariform teeth. 
Color of type-specimen.—Vace markings sharply drawn, brownish- 
black and whitish. Upperparts from crown to base of tail dark blackish- 
gray, the coat sliort and harsh; underfur dull Trout’s brown, hairs 
ringed with bull' and tiiiped with black; a distinct narrow line of black 
from between ears to withers. Arms, hamls, and feet l)uffy; legs like 
back and hips. Tail ringed with black and j)ale orange-yellow, the ti]> 
black. 
Skull and teeth.—^knW essentially as in Procyon lotor hernandezii; the 
molariform teeth all decidely larger. 
Measurements of type, from well made dry skin.—Head and body, 600; 
tail, 325; hind foot, 118. Skull: Condylobasal length, 123; palatal 
length, 77.1; zygomatic breadth, 75.5; nasals, greatest length, .34.5; 
interorhital breadth, 25.7; mastoid breadth, 65.8; mandihle, 91.3. Teeth, 
Upper row, c-m\ 48; pnd-nd, 31; pm^-ni\ 25.1; width p»T, 10; width 
m^, 10.5; lower row, pmi~m 2 , 46.4. 
* Rev. Primates, vol. 2, pp. 21-48, 1913. 
