94 SCIURUS. 
Parasciurus Treuss., Le Nat., 11, 1880, p. 292. 
Echinoscturus Treuss., Le Nat., 11, 1880, p. 292. 
Tamiasciurus Treuss., Le Nat., 11, 1880, p. 292. 
Microsciurus Allen, Bull. Am. Mus. Nat. Hist., 1895, p. 332. 
Hesperoscturus, Nelson, Proc. Wash. Acad. Scien., 1, 1899, p. 27. 
Otosciurus, Nelson, Proc. Wash. Acad. Scien., 1, 1899, p. 28. 
Are@osciurus Nelson, Proc. Wash. Acad. Scien., 1, 1899, p. 29. 
Batosciurus Nelson, Proc. Wash. Acad. Scien., 1, 1899, p. 31- 
Tail broad long, bushy, hairs mostly directed laterally; ears 
moderate, hairy, sometimes with long tufts at tip; no cheek pouches. 
Skull rather short, broad; postorbital processes directed downward 
and backward and well developed; one upper premolar, sometimes 
two; in the latter case the first is always very small; antorbital 
foramen slit-like, placed anteriorly to the zygomatic process of the 
maxillary. 
KEY FO THE SPECIES ANDISUBSPEGIE=: 
*A. Size small, total length under 450 mm., but above 300 mm. PAF 
a. Premolars —; ears medium long, thinly haired. 
a.’ Tail washed with bright ferrugineous...S.@. hojffmannit 104 
be “Caihwashed with -tawaiiyn. cs ee aoe S.@. chiriquensis 104 
ce, Mail washed cwith yellowish. =. ater S. richmondit 105 
b. Premolars =, 
a.’ Ears small or medium, not tufted. 
a.” Ears short, rounded, thickly haired; 
total length under 300 mm. 
a. Tail washed. with reddish: -sa- aa ae S..aljars 9a 
b.’’’ Tail washed with grayish white....... S. brownt 100 
ce.’ Tail washed with tawny olive....S. boquetensis 100 
b.”’ Ears medium long, pointed, thinly 
haired; total length over 300 mm. 
avi: ‘Backvona visits bn@wilesstes sae serene S. negligens 102 
b.’’’ Back reddish or yellowish brown....... S. depp 101 
c.’*. Back ‘rusty reddish) say “saree ee S.d. vivax 102 
“= or —. 
ey Eremolars on 
a.’ Ears large, tufted. 
a.’’ Back gray, belly white, lateral line 
[Ov el GR ae Pe Meee Ra EM HS Gre ho S. d. mearnst 133 
* The construction of an intelligible key for the endless variations displayed 
by the members of the genus Sczuwrus is an almost insuperable task, and may 
not be attempted unless specimens of all the species are available at one time. 
This not having been possible for the author to accomplish, the present key for 
the species, with some few additions, has been taken from E. W. Nelson's 
‘Revision of the Squirrels of Mexico and Central America.” 
