_Pipistrellus cinnamomeus_ Miller, Proc. Acad. Nat. Sci.
Philadelphia, p. 390, September 3, 1902, type from
Montecristo, Tabasco (preoccupied by _Vespertilio
cinnamomeus_ Wagner, Schreber's Saeugethiere, suppl., 5:755,
1855, a renaming of _Vespertilio ruber_ E. Geoffroy
Saint-Hilaire).
_Myotis lucifugus fortidens_ Miller and Allen, Bull. U. S.
Nat. Mus., 144:54, May 25, 1928.
_Type._--"Adult female (in alcohol) No. 88.8.8.18, British Museum
(Natural History). Collected at Teapa, Tabasco, Mexico, by H. H. Smith,
January 5, 1888. Presented by Messrs. Salvin and Godman [after Miller
and Allen, Bull. U. S. Nat. Mus., 144:54, May 25, 1928]."
_Range._--Known only from the lower part of the Tropical Life-zone of
the region of the Isthmus of Tehuantepec and east and west coasts of
Mexico.
[Illustration: FIG. 1. Map showing localities from which _Myotis
fortidens_ has been recorded.]
_Diagnosis._--Among American species of the genus, over-all size medium
(total length 94 mm); body long (54); tail short (39); forearm of medium
length (37); tibia short (14.5); foot long (58 per cent of length of
tibia); wing membrane arising from side of foot at distal end of
metatarsal; calcar simple (not keeled) and 7 mm long; ears 15 to 16 mm
long measured in the flesh from the notch (posteroventral border of the
meatus); tragus, measured from same place, 7 to 8 mm high with
posterobasal lobe; third metacarpal longest and second metacarpal
shortest; fifth shorter than fourth; ears brownish; membranes of wing
and tail blackish; uropatagium almost hairless, the few hairs that are
present being almost invisible; pelage of back 5 mm long with some
overhairs 8 to 9 mm long; basal 3 mm of fur black, remainder
Cinnamon-Brown (capitalized color terms, after Ridgway, Color Standards
and Color Nomenclature, Washington, D. C., 1912); outline of skull
viewed dorsally similar to that of _Myotis lucifugus_; sagittal crest
well developed; distance across upper canines equal to or slightly
exceeding interorbital constriction; braincase low; two premolars on
each side in upper jaw and also in lower jaw, the one remaining small
premolar in contact with both the canine and the fourth premolar.
[Illustration: FIGS. 2-5. Four views of the skull of _Myotis fortidens_.
No. 32112, University of Kansas Museum of Natural History, [M], obtained
20 kilometers east-northeast Jesus Carranza, 200 feet elevation,
Veracruz, Mexico, on May 16, 1949, by Walter W. Dalquest; original no.
12869. x2.]
_Remarks._--_Myotis fortidens_ is known only from the Tropical
Life-zone. The skin, without a skull, from Esquinapa, Sinaloa, agrees in
color with the undoubted specimens of _M. fortidens_ from Papayo,
Guerrero, but can be matched also by selected skins of _Myotis occultus_
from Blythe, Riverside County, California. Without the skull the
reference of this specimen to _M. fortidens_ is provisional. Reason for
referring it to _fortidens_ rather than to _M. occultus_ is provided,
however, by a series of eleven specimens of _M. occultus_ from Alamos,
Sonora. These are Saccardo's Umber rather than Cinnamon-Brown and they
are geographically intermediate between the reddish _M. occultus_ of
California and the reddish _M. fortidens_ of Mexico. Furthermore, these
specimens from Alamos have large skulls of slightly different
proportions than those of _M. fortidens_ or than those of _M. occultus_
from California; possibly the animals from Alamos are representative of
the larger, duller-colored variation for which Hollister proposed the
name _Myotis baileyi_ (Proc. Biol. Soc. Washington, 22:44, March 10,
1909). This duller-colored type of animal intervenes between the
geographic ranges of undoubted _M. occultus_ and undoubted _M.
fortidens_. The specimen from Esquinapa, in the geographic sense, is on
the _fortidens_ side rather than on the _occultus_ side of the _baileyi_
population. This geographic position is the basis on which the specimen
from Esquinapa is referred to _M. fortidens_. The third premolar is
lacking from each side of both the upper and the lower jaws of each
individual of this series from Alamos.
The specimens of _M. fortidens_ are all distinguishable by their color
from other kinds of _Myotis_ found in the same area. Occasional
individuals of _Myotis velifer_, as for example three from Las Vigas,
Veracruz, also are reddish but they are of brighter tone. In addition,
the larger size and cranial features of these specimens of _M. velifer_
permit ready differentiation of them from specimens of _M. fortidens_.
One specimen (No. 32113) of _M. fortidens_ from twenty kilometers
east-northeast of Jesus Carranza is lighter than the others, being near
(_j_) Cinnamon-Brown above and is lighter on the under-parts than on the
upper parts. Another individual (No. 32112) is duller colored than the
others, being Snuff Brown both above and below. Otherwise the specimens
of _M. fortidens_ agree in color.
Among named kinds of _Myotis_, _M. fortidens_ resembles _Myotis
lucifugus_ and _Myotis occultus_. From the former, _M. fortidens_
differs in possessing a strong sagittal crest and in lacking the third
premolar in both the upper jaw and the lower jaw. _M. fortidens_ lacks
the glossy sheen found on the pelage of many individuals of _M.
lucifugus_. From _M. occultus_, _M. fortidens_ differs in having the
rostrum (viewed from above) smaller in relation to the braincase. This
is true of specimens with the teeth showing much wear as well as in
specimens with the teeth unworn or only moderately worn. Also, _M.
fortidens_ is longer bodied as may be seen by comparing the measurements
given here with those recorded for _M. occultus_ by Miller and Allen
(Bull. U. S. Nat. Mus., 144:100, May 25, 1928). We are agreed that _M.
fortidens_ is as closely related to _M. occultus_ as to any other named
kind of _Myotis_, and that it is more closely related to it than to most
other species of the genus, but one of us (Dalquest) thinks that _M.
fortidens_ is specifically distinct from _M. occultus_, whereas the
other author (Hall) inclines to the view that additional specimens from
localities intermediate between the known geographic ranges of _M.
occultus_ and _M. fortidens_ will reveal intergradation between the two
kinds. However that may be, there is no proof at present of such
intergradation and the binomial is therefore used for the Cinnamon
Myotis.
_Specimens examined._--Total number, 10, all from Mexico,
each a skin with skull except the skin-only from Sinaloa.
_Sinaloa_: Esquinapa, 1 (Amer. Mus. Nat. Hist.). _Guerrero_:
Papayo, 2 (U. S. Biological Surveys Collection). _Veracruz_:
20 km. WNW Piedras Negras, 3 (Mus. Nat. Hist., Univ.
Kansas); 20 km. ENE Jesus Carranza, 200 ft. elevation, 3
(Mus. Nat. Hist., Univ. Kansas). _Tabasco_: Montecristo, 1
(U. S. Biological Surveys Collection).
_Additional record._--Tabasco: Teapa, the holotype of
_Myotis lucifugus fortidens_ Miller and Allen 1928.
_University of Kansas Museum of Natural History, Lawrence, Kansas.
Transmitted October 31, 1949._