pus castaneiceps_ (type locality, Chontales,
Nicaragua) in "nasals shorter, with anterior border concave or
emarginate, the emargination deepest at median suture; squamosal arm of
zygoma broader, more rounded, less acutely pointed anteriorly; palate
less deeply grooved posteriorly; symphysis of mandible less produced
anteriorly beyond plane of first molars." Later, Goldman (Smiths. Misc.
Coll., 69(5):57-58, April 24, 1920) arranged _Bradypus castaneiceps_ as
a subspecies of _B. griseus_, reaffirmed the full specific identity of
_Bradypus ignavus_, and identified specimens from Tapalisa, Cituro, and
Real de Santa Maria, all in eastern Panama, as belonging to _B.
ignavus_.

In order to satisfy ourselves about the taxonomic relationship of _B.
ignavus_ to _B. griseus_, we have examined the following materials in
the American Museum of Natural History: _ignavus_: Panama: Cituro (No.
38191), Tapalisa (No. 38102), Real de Santa Maria (Nos. 37619-37621);
_griseus_: Panama: La Chorrera (No. 31427); Costa Rica: Juan Vinas (No.
2824), Palmar (No. 139313), Vijagual, San Carlos (No. 139833);
_castaneiceps_: Nicaragua: Chontales (Nos. 28477 and 28478).

The specimens from Real de Santa Maria, Tapalisa, and Cituro, average
darker than all others, but this darkness is approached in certain
specimens of _griseus_ (for example, No. 139833, from Vijagual, San
Carlos). The broader, more rounded and less acutely pointed squamosal
arm of the zygoma supposedly characteristic of _ignavus_ is matched in
certain specimens of _griseus_ (for example, in No. 2824 from Juan
Vinas, Costa Rica) and the character is variable among specimens
referred to _ignavus_; the shape of the squamosal arm is of doubtful
taxonomic worth in the present connection. The depth of the grooving on
the palate seems to vary with age and is of questionable value
taxonomically. The emarginate nasals of _ignavus_ are matched in
_griseus_ (No. 139833) from Vijagual, San Carlos, Costa Rica. The
extension of the anterior symphyseal region of the mandible is short in
_ignavus_; the specimen with the longest extension (No. 37621 from El
Real), however, has the extension only barely shorter than does No.
139933 of _griseus_ from Vijagual, San Carlos, Costa Rica. In brief,
while we see the characters of _ignavus_ as set forth by Goldman (_op.
cit._), we find them to be of only an average sort and not pronounced.
Further, a specimen (No. 139833) from Vijagual, San Carlos, Costa Ric