adically in other populations, the animals from the higher
elevations above Jico and Las Vigas are notably homogeneous, differ
collectively from surrounding populations, and occupy a logical
geographic range. Therefore _S. a. frumentor_ is retained as a tenable
subspecies, and the animals from the vicinity of San Marcos, and from
San Carlos and Plan del Rio are referred to _S. a. aureogaster_.
Incidentally, Nelson (_op. cit._:45) remarks that he saw no melanistic
specimens of _S. a. frumentor_. This is not strange because melanistic
specimens could not be identified anyway.

[Illustration: FIG. 1. Geographic distribution
of _Sciurus aureogaster_.
1. _Sciurus aureogaster aureogaster._
2. _Sciurus aureogaster frumentor._]

The names, absolute synonyms, and geographic ranges of the two
subspecies of _Sciurus aureogaster_ here recognized are as follows:

SCIURUS AUREOGASTER AUREOGASTER F. Cuvier

1829. _Sciurus aureogaster_ F. Cuvier, Hist. Nat. Mammiferes,
VI, livr. LIX, pl. with text.

1830. _Sciurus rafiventer_ Lichenstein, Abhandl. K. Akad.
Wiss., Berlin, p. 116 (1827).

1831. _Sciurus leucogaster_ F. Cuvier, Suppl. d'Hist. Nat.
Buffon, pp. 300, 301.

1831. _Sciurus hypopyrrhus_ Wagler, Oken's Isis, pp. 510,
511.

1841. _Sciurus mustelinus_ Audubon and Bachman, Proc. Acad.
Nat. Sci. Philadelphia, pp. 100, 101.

1841. _Sciurus ferruginiventris_ Audubon and Bachman, Proc.
Acad. Nat. Sci. Philadelphia, p. 101.

1845. _Sciurus ferrugineiventris_ Schinz, Synopsis Mamm., II,
p. 14.

1855. _Sciurus hypoxanthus_ (Lichenstein MS) Geoffroy, Voyage
de la Venus, Zool. (text), pp. 158, 159 (on labels of
squirrels from Berlin Museum, _fide_ Nelson, Proc. Washington
Acad. Sci., 1:38, May 9, 1899).

1855. _Sciurus chrysogaster_ Giebel, Saugethiere, p. 650.

1867. _Macroxus aureogaster_ Gray, Ann. and Mag. Nat. Hist.,
ser. 3, 20:423.

1867. _Sciurus hypopyrrhous_ Gray, Ann. and Mag. Nat. Hist,
ser. 3, 20:424.

1867. _Macroxus morio_ Gray, Ann. and Mag. Nat. Hist., ser.
3, 20:424.

1867. _Macroxus maurus_ Gray, Ann. and Mag. Nat. Hist., ser.
3, 20:425.

1887. _Sciurus rufiventris?_ Rovirosa, La Naturaleza, 7:360
(1885-1886).

1897. _Sciurus leucops_ Allen, Bull. Amer. Mus. Nat. Hist.,
9:198.

1899. _Sciuru