t this seems not to be significant
taxonomically, because examination of series from other localities
provides no evidence of geographic variation in color except,
possibly, in the frequency of melanism. A series of 13 specimens
(Univ. Kansas) from 7 and 8 km. WNW Potrero, Veracruz, for example, is
quite as dark as topotypes of _S. a. hypopyrrhus_ from Miniatitlan,
although the localities of capture are approximately in the center of
the geographic range of _S. a. aureogaster_. In short, there seems to
be no way to distinguish _S. a. hypopyrrhus_ from _S. a. aureogaster_
on the basis of color. An unusual amount of variation exists, but it
seems to occur at random. Fixing type localities of the two subspecies
at the places of origin of certain specimens which in color fit the
original descriptions is meaningless because selected specimens or
series from almost any place in the geographic range of the species
would qualify as approximate color-duplicates of the types.

My findings agree with those of Nelson in that skulls from Miniatitlan
average longer and narrower than those from Altamira, but this seems
not to be significant taxonomically because the series from Altamira
is, to judge from the material I have seen, somewhat shorter and
broader cranially than is "average" for the alleged subspecies _S. a.
aureogaster_. For example, series from Metlaltoyuca in Puebla, 3 km. E
Axtla in San Luis Potosi, 8 km. NW Potrero and 20 km. NW Piedras
Negras in Veracruz, although obtained from localities well within the
geographic range of _S. a. aureogaster_ (as outlined by Nelson), all
more closely resemble the "topotypes" of _S. a. hypopyrrhus_ in
cranial measurements than they do "topotypes" of _S. a. aureogaster_.
Conversely, specimens from that part of the range of _S. a.
hypopyrrhus_ most remote from the range of _S. a. aureogaster_
(Montecristo, La Venta, and Teapa, all in Tabasco) more closely
approximate the Altamiran series in cranial size and proportions than
they do the Miniatitlan material. Therefore, my data contradict the
statement of Nelson (_loc. cit._) that the skulls of _S. a.
hypopyrrhus_ are larger but proportionately narrower than those of
_S. a. aureogaster_. The constriction of the auditory bullae alluded
to by Nelson as being present in _S. a. hypopyrrhus_ is also present
in _S. a. aureogaster_, occurring in both subspecies in varying
degrees without correlation with geographic distribution.

Actually, the