Brown); proximal fourth of individual guard hairs of dorsum
black-tipped, distal three-fourths dark grayish; dorsal underfur
black-tipped having subterminal band of Buffy Brown; hair around eyes
buffy to base; belly Pallid Neutral Gray with overtones of buff;
individual hairs in region of chin whitish-gray to bases; vibrissae
blackish to bases except ventralmost, those being white to base; tail
Dark Olive above, slightly paler below. Average and extreme external
measurements of 13 adults from 15 mi. N Rosario, Chele, Sinaloa, 300
ft., are as follows: Total length, 109.6 (99-120); length of tail, 43.4
(38-49); length of body, 66.2 (58-75); length of hind foot, 11.2
(10-12). Average and extreme cranial measurements of 19 adults from the
same place are as follows: occipitonasal length, 18.2 (17.7-18.9);
zygomatic breadth, 9.6 (9.2-10.1); postpalatal length, 6.9 (6.5-7.3);
least interorbital breadth, 3.6 (3.4-3.8); length of incisive foramina,
3.9 (3.5-4.2); length of rostrum, 5.9 (5.5-6.6); breadth of braincase,
8.7 (8.3-8.9); depth of cranium, 6.5 (6.2-6.7); alveolar length of
maxillary tooth-row, 3.1 (3.0-3.2); breadth of zygomatic plate, 1.8
(1.6-2.0); for photographs of skull, see Plate 2_c_, and Plate 4_d_.
_Comparisons._--From _B. t. ater_, _B. t. canutus_ differs in: dorsum
slightly grayer; belly whitish to pale-gray with only faint tones of
buff, rather than cinnamon-buff to buff-gray; forefeet and hind feet
flesh-colored to grayish above instead of whitish to flesh-colored; tail
paler above, less hairy, scales more evident; interparietal relatively
larger from anteriormost to posteriormost points; incisive foramina
tapering less abruptly posteriorly, not constricted towards midline;
over-all size of body and cranium somewhat larger.
From _B. t. paulus_, _B. t. canutus_ differs in: dorsum grayish-brown
rather than fawn-colored (not differing appreciably from extremes of
darker brown specimens of _paulus_); forefeet and hind feet
flesh-colored to grayish above rather than white above; tail less
hairy, unicolored to faintly bicolored rather than distinctly bicolored;
braincase slightly larger; alveolar length of maxillary tooth-row
slightly less.
From _B. t. analogous_, _B. t. canutus_ differs in: dorsum paler, less
of dark brown hues; belly paler; forefeet and hind feet slightly paler,
less sooty above; tail less hairy, paler and having scales evident;
jugal of zygoma extending ventrally to a point immediately above,
instead of below, level of alveolus of upper molars; nasals more nearly
truncate anteriorly; infraorbital foramina less deeply notched toward
midline of skull; body and skull averaging smaller throughout.
From _B. t. allex_, _B. t. canutus_ differs in: dorsal ground color
grayish rather than fawn color having grayish overtones; underfur on
dorsum darker gray; dorsal surface of forefeet and hind feet
flesh-colored to grayish rather than flesh-colored; incisive foramina
tapering to a point posteriorly rather than rounded posteriorly;
interparietal relatively smaller; body and skull averaging larger
throughout.
_Remarks._--Burt (1938:54) reluctantly assigned specimens from Ciudad
Obregon to _B. t. paulus_, probably being influenced by the resemblance
in size. He suggested that, perhaps, a distinct subspecies occurs in the
State of Sonora. Study of larger series of specimens than were available
to Burt reveals that populations of pygmy mice inhabiting the northwest
coastal plains of Mexico are indeed distinct.
The darkest of the material assigned to _canutus_ is from Nayarit (for
specific localities see specimens examined). According to Tamayo
(1949:Carta de Suelos), color of soil changes from chestnut in northern
Sinaloa to black in southern Sinaloa and northern Nayarit. There seems,
therefore, to be a close correlation between color of pelage and color
of soil in this area. In Nayarit, particularly in the central and
southern parts, the mice are intermediate in color between the paler,
grayer population to the north and the more brownish samples,
representative of _allex_ to the south. The coastal vegetation changes
from the arid tropical thorn forests of the north and central parts of
Sinaloa to a savannah in Nayarit, thence to a tropical deciduous forest
farther south (see Leopold, 1950:508).
In size and color, specimens from 3 mi. SE Tepic and 2 mi. SW Rosa
Morada are intermediate between the larger, grayer _canutus_ and the
smaller, light-brownish _allex_. In size of cranium, these specimens are
more nearly like _canutus_, and are referred to that subspecies. Mice
from the western coastal plain are relatively homogeneous as regards
size of body and skull, except that those from 13.5 mi. S Acaponeta,
Nayarit, average somewhat larger.
_B. t. canutus_, like _B. t. subater_, is predominantly a lowland or
coastal subspecies. The pallor of the former, that lives on generally
paler soils, presumably is of adaptive value.
Pygmy mice are seemingly rare in the northern part of the range of this
subspecies. J. Raymond Alcorn and Albert Alcorn were successful in
collecting only two specimens from the type locality after three
successive nights of trapping with 100 traps set each night. Only six
specimens are known from Sonora. These were obtained in the irrigated
regions of Ciudad, Obregon, and Navajoa. Charles Sibley obtained one
specimen 10.6 mi. SE Ciudad Obregon in a "maguey field." I obtained one
specimen 1 mi. NNW Navajoa in a sparse grassway, 20 feet wide, bordering
an open sewer, which coursed northward into the Rio Mayo. Irrigated
wheat fields bordered the grassway and ditch.
_Specimens examined._--Total 70 all from the Republic of Mexico and
distributed as follows: SONORA: [Ciudad] Obregon, 4[44]; 10.6 mi. SE
[Ciudad] Obregon, 1[45]; 1 mi. NNW Navajoa, 1. SINALOA: type locality, 2
(including the type); Culiacan, 175 ft., 2[46]; Mazatlan, 1[48]; _15 mi. N
Rosario, Chele_, 300 ft., 35[47]; Rosario, 3[46]; Escuinapa, 5[48];
_Railroad Station Escuinapa_, 43 ft., 2[45]. NAYARIT: Acaponeta, 4[46];
_13.5 mi. S Acaponeta Junction_, 6[49]; 2 mi. SW Rosa Morada, 2; _2 mi.
WNW Tepic_, 3200 ft., 1; 3 mi. SE Tepic, 1.
_Marginal records._--SONORA [Ciudad] Obregon. SINALOA: type locality;
Escuinapa. NAYARIT: Acaponeta; 3 mi. SE Tepic. SINALOA: Mazatlan.
[44] Coll. Univ. California, Los Angeles.
[45] Univ. California, Mus. Vert. Zoology.
[46] U. S. Nat. Museum (Biol. Surv. Coll.).
[47] Univ. Michigan, Museum of Zoology.
[48] American Museum of Natural History.
[49] Univ. Illinois, Mus. Nat. History.
=Baiomys taylori fuliginatus=, new subspecies
_Baiomys taylori taylori_, Dalquest, Louisiana State Univ. Studies
(Biol. Sci. Ser.) 1:155, December 28, 1953 (part).
_Baiomys taylori taylori_, Booth, Walla Walla Publs. Dept. Biol.
Sci., 20:15, July 10, 1957 (part).
_Type._--Adult male, skin and skull; No. 36765, University of Kansas,
Museum of Natural History; 10 mi. E, 2 mi. N Ciudad del Maiz, 4000 ft.,
San Luis Potosi, Republic of Mexico; obtained on January 17, 1950, by J.
R. Alcorn, original number 10400.
_Range._--Occurs in the Sierra Madre Oriental of the northeastern third
of San Luis Potosi. Zonal range: Upper Tropical (see Dalquest, 1953:10);
approximates a part of the Sierra Madre Oriental Biotic Province of
Goldman and Moore (1945:349, 356). Occurs from 2000 feet at El Salto up
to 4000 feet at Ciudad del Maiz.
_Diagnosis._--Size large for the species; ground color of dorsum
Chaetura Drab; individual guard hairs of dorsum black to base, distal
fourth of hairs of underfur in posterior half of dorsum tipped with
grayish-brown, proximal three-fourths Dark Neutral Gray; in anterior
region of dorsum, posterior to ears, distal third of hairs grayish-brown
and proximal two-thirds Dark Neutral Gray to base; sides slightly paler
than dorsum; ground color of belly Neutral Gray, individual hairs of
belly and throat tipped with Pallid Neutral Gray, basally Deep Neutral
Gray to Dark Neutral Gray; tips of individual hairs of face
Ochraceous-Tawny; lateral vibrissae whitish, dorsal and ventral
vibrissae black to base; forefeet and hind feet sooty above and below,
thigh bearing some white-tipped hairs; tail near Chaetura Drab above,
Pale Neutral Gray below; anterior part of jugal projecting slightly
ventrally and forming small protuberance at point of articulation with
maxillary part of zygoma; jugal extending anteriorly nearly to lacrimal.
In most cranial measurements averaging as large as _B. t. analogous_.
Average and extreme measurements of the type and three additional
paratypes, all adults, are: total length, 105.5 (101-109); length of
tail, 39.8 (35-42); length of body, 65.8 (63-68); length of hind foot,
14.3 (14-15); length of ear from notch, 11 (11); occipitonasal length,
18.1 (18.1-18.8); zygomatic breadth, 9.6 (9.3-9.8); postpalatal length,
6.5 (6.0-6.7); least interorbital breadth, 3.4 (3.3-3.6); length of
incisive foramina, 4.0 (3.8-4.2); length of rostrum, 6.3 (6.1-6.4);
breadth of braincase, 8.8 (8.6-8.9); depth of cranium, 6.7 (6.5-6.8);
alveolar length of maxillary tooth-row, 3.2 (3.1-3.3); for photograph of
skull, see Plate 2_d_, and Plate 4_e_.
_Comparisons._--From _B. t. taylori_, _B. t. fuliginatus_ differs in:
dorsum slightly darker than in darkest _taylori_; tail densely haired,
bicolored rather than unicolored; belly sooty to grayish rather than
grayish to whitish; forefeet and hind feet sooty to grayish rather than
flesh-colored; incisive foramina less bowed laterally, more nearly
straight; interparietal compressed anteroposteriorly, less
diamond-shaped.
From _B. t. paulus_, _B. t. fuliginatus_ differs in: dorsum dusky to
blackish rather than fawn color; belly sooty to grayish rather than
buffy to whitish-gray; forefeet and hind feet sooty to grayish rather
than whitish; zygoma more nearly forming a right angle with rostrum or
skull, less tapered anteriorly; anterior part of jugal possessing
ventral projection; jugal extending nearly to lacrimal on posterior
surface of maxillary part of zygoma.
From _B. t. analogous_, _B. t. fuliginatus_ differs in: mid-dorsal
region blacker, less brownish; tail distinctly bicolored rather than
unicolored to faintly bicolored; incisive foramina not constricted
medially; presphenoid broader (at narrowest point); jugal differs much
the same as it does from _paulus_; nasals anteriorly truncate instead of
rounded.
_Remarks._--Dalquest (1953:155-157) and Booth (1957:15) assigned all of
the pygmy mice that they examined from the state of San Luis Potosi to
_B. t. taylori_. Examination of all of the material that was available
to Dalquest, plus additional specimens at the University of Kansas
Museum of Natural History, reveals that there are three subspecies in
San Luis Potosi. _B. t. taylori_ occurs in the eastern part of the State
at lower altitudes; _B. t. analogous_ occurs to the southeast at higher
altitudes; _B. t. fuliginatus_ occurs in the northeastern part of the
State in the Sierra Madre Oriental.
Specimens obtained from Ebano, Pujal, and Tamuin, representative of _B.
t. taylori_, are much paler on the belly and on the ventral surface of
the forefeet and hind feet than are specimens from Ciudad del Maiz,
representative of _B. t. fuliginatus_. The tail in _B. t. taylori_ is
nearly unicolored and less hairy than in the paratypical series of
_fuliginatus_. Specimens from 4 km. NE Ciudad Valles are nearly
intermediate in color of the belly, dorsum, forefeet and hind feet, and
tail, between the palest mice from the coastal plain and the darker mice
in the mountains of the northeastern part of the State (specimens from
El Salto average paler, however, than the type and paratypes). These
specimens seem to be intergrades between _B. t. taylori_ to the east on
the coastal plain and _fuliginatus_ to the northwest in the mountains.
It seems best to refer the mice from 4 km. N Ciudad Valles to _B. t.
taylori_ on the basis of the average of external and cranial characters.
Specimens from 6 mi. SW San Geronimo, Coahuila, also referred to _B. t.
taylori_, resemble in color the mice from 4 km. N Ciudad Valles. When
more specimens are obtained from the front range of the Sierra Madre
Oriental, at lower altitudes, the manner in which these two subspecies
intergrade with one another will be better understood. At present,
populations from higher altitudes in the mountains seem to represent a
dark subspecies; populations from the coastal plain represent a pale
subspecies, and those from the lower slopes and high valleys seemingly
are intergrades. _B. t. fuliginatus_ occurs in a somewhat limited strip
of chernozem soil (or suelos negros of Tamayo, 1949: Carta de Suelos).
The populations occurring at lower altitudes on the coastal plain are on
generally paler soils.
_Specimens examined._--Total 39, all from the Republic of Mexico, as
follows: SAN LUIS POTOSI: El Salto, 24 Mus. Nat. Hist., Louisiana State
Univ., 7 Amer. Mus. Nat. Hist.; type locality, 8 (including the type).
_Marginal records._--See specimens examined.
=Baiomys taylori paulus= (J. A. Allen)
_Peromyscus paulus_, J. A. Allen, Bull. Amer. Mus. Nat. Hist.,
19:598, November 12, 1903; Elliot, Field Columb. Mus. Publ.,
105(6): 136, July 1, 1905.
_Baiomys taylori paulus_, Miller, Bull. U. S. Nat. Mus., 79:137,
December 31, 1912 (part); Miller, Bull. U. S. Nat. Mus., 128:317,
April 29, 1924 (part); Ellerman, The Families and Genera of Living
Rodents, 2:402, March 21, 1941 (part); Goldman, Smith, Miscl. Coll.,
115:373, July 31, 1951 (part); Hall and Kelson, Univ. Kansas Publs.,
Mus. Nat. Hist., 26:367, December 15, 1952; Goodwin, Bull. Amer.
Mus. Nat. Hist., 102:318, August 31, 1953; Miller and Kellogg, Bull.
U. S. Nat. Mus., 205:511, March 3, 1955 (part); Packard, Proc. Biol.
Soc. Washington, 71:17, April 11, 1958; Packard, Jour. Mamm.,
40:146, February 20, 1959; Hall and Kelson, The Mammals of North
America, 2:659, March 31, 1959 (part).
[_Peromyscus_] _paulus_, Elliot, Field Columb, Mus. Publ.,
95(4):136, July 15, 1904.
_Peromyscus taylori paulus_, Osgood, N. Amer. Fauna, 28:255, April
17, 1909 (part).
_Peromyscus musculus_ [_musculus_], Osgood, N. Amer. Fauna, 28:256,
April 17, 1909 (part).
_Baiomys taylori_ [= _paulus_], Twente and Baker, Jour. Mamm.,
32:121, February 15, 1951.
_Baiomys musculus musculus_, Goldman, Smith. Miscl. Coll., 115:336,
July 31, 1951 (part).
_Baiomys taylori allex_, Hall and Kelson, The Mammals of North
America, 2:659, March 31, 1959 (part).
_Type._--Adult male, skin and skull; No. 21165, American Museum of
Natural History; Rio Sestin, Durango, Republic of Mexico; obtained on
April 15, 1903, by J. H. Batty, original number 455.
_Range._--Central Chihuahua south through Durango (west to eastern edge
of Sierra Madre Occidental), to Zacatecas and Aguascalientes, thence
west into northern and northwestern Jalisco, see Figure 11. Zonal range:
Lower Sonoran, approximately the Chihuahua Desert Biotic Province of
Goldman and Moore (1945:349). Occurs from 4000 feet 2 mi. ESE Tequila,
Jalisco, up to 6700 feet 2 mi. W Minaca, Chihuahua.
_Diagnosis._--Size medium to small for the species; dorsum Buffy Brown
to fawn color; dorsal ground color of unworn pelage of adults varying
from Buffy Brown in darkest series (especially those from higher
altitudes) to Avellaneous with grayish overtones in palest series; worn
pelage in mid-dorsal region of adults fawn to grayish; terminal parts of
individual hairs buffy, gray basally; guard hairs on dorsum
black-tipped, grayish basally; belly Light Gull Gray, distal half of
hairs white, proximal half Neutral Gray; hairs in region of throat and
chin white to base (some specimens with faint buffy overtones); forefeet
dusky below, whitish above; hind feet whitish above, ventral surface
whitish to dusky; dorsal and lateral vibrissae black, other vibrissae
white. Average and extreme measurements of six adults from the type
locality are as follows: total length, 109 (106-117); length of tail,
44.5 (43-48); length of body, 63 (57-69); length of hind foot, 13.1
(12.7-14.0); occipitonasal length, 17.5 (17.4-18.0); zygomatic breadth,
9.3 (9.1-9.5); postpalatal length, 6.6 (6.2-6.9); least interorbital
breadth, 3.5 (3.4-3.6); length of incisive foramina, 3.8 (3.6-4.1);
length of rostrum, 5.9 (5.7-6.0); breadth of braincase, 8.6 (8.5-8.8);
depth of cranium, 6.6 (6.2-6.9); alveolar length of maxillary tooth-row,
3.2 (3.1-3.4); for photographs of the skull, see Plate 2_e_ and Plate
4_f_.
_Comparisons._--For comparisons with _B. t. allex_, _B. t. canutus_, _B.
t. ater_, and _B. t. taylori_, see accounts of those subspecies. From
_B. t. analogous_, _B. t. paulus_ differs as follows: dorsal color paler
having more reddish-brown than blackish-brown tones; venter whitish to
buffy, instead of gray to light-gray; tail bicolored (not unicolored),
usually having more hairs; hind feet white (not sooty) above. Cranially,
_B. t. paulus_ differs from _B. t. analogous_ in: skull slightly smaller
in all dimensions; maxillary part of zygoma narrowing and forming
oblique angle rather than a near right angle with rostrum; anterior
incisive foramina constricted posteriorly; tips of nasals truncate (less
rounded).
_Remarks._--J. A. Allen (1903:599) correctly pointed out that young
specimens, in first pelage, were gray brown; young adults were darker
and more varied with some blackish; adults and old adults were buffy to
grayish. The change in color of pelage with increasing age is more
pronounced in _paulus_ than in other subspecies of _B. taylori_. Of two
males collected on April 12, 1949, one, an adult, is buffy brown, and
the other, an old adult with worn pelage, is grayish-brown. In mice in
the earlier stages of adulthood, underfur of the dorsum is buffy at the
tips and gray basally. With increased wear, the buffy tip is lost.
Consequently, mice in the later stages of adulthood are grayish.
_B. t. paulus_ intergrades with _ater_ to the north in Chihuahua (see
account of that subspecies), with _analogous_ to the south in Jalisco,
and with _allex_ (see account of that subspecies) to the southwest in
Nayarit and Jalisco. The zone of intergradation between _paulus_ and
_analogous_ in Jalisco approximately borders the Rio Grande de Santiago
from the western part of the State to the northwest shore of Lago de
Chapala. Nineteen specimens from 2 mi. WNW Lagos de Moreno in northwest
Jalisco seem to be intermediate between _paulus_ and _analogous_ in
color, averaging slightly grayer than typical _paulus_. The series of 19
is referable to _paulus_ on the basis of cranial characters.
A series of 34 specimens from 3 mi. W La Venta, Jalisco (referable to
_paulus_), is indistinguishable in color of pelage from two series of
_paulus_ from 5 mi. N Durango, and from 8 mi. NE of Durango, except that
the antiplantar surfaces of the hind feet are sooty as in _analogous_.
Seemingly, features of color mentioned above as diagnostic of the two
subspecies are either present or absent and there is no tendency toward
intermediacy in color in the population from 3 mi. W La Venta.
The Rio Grande de Santiago may have acted in the past as a physical
barrier reducing gene flow between _allex_ and _paulus_ and in
separating completely the two populations for limited periods.
_Specimens examined._--Total 176, all from the Republic of Mexico and
distributed as follows: CHIHUAHUA: Rancho Sanignacio, 4 mi. S, 1 mi. W
Santo Tomas, 1; El Rosario, 6700 ft., 1; 2 mi. W Minaca, 6900 ft., 11;
Balleza, 1[50]. DURANGO: Rosario, 1[51]; type locality, 14[51] (including
the type); _San Gabriel_, 2[51]; _Rancho Santuario_, 2[51]; 1 mi. N
Chorro, 6450 ft., 1; _8 mi. NE Durango_, 6200 ft., 2; 5 mi. N Durango,
6400 ft., 2. ZACATECAS: Valparaiso, 6500 ft., 10[50]. AGUASCALIENTES: _18
mi. W, 2 mi. S Aguascalientes_, 6000 ft., 1; 16 mi. S Aguascalientes,
5[52]. JALISCO: 1 mi. NE Villa Hidalgo, 6500 ft., 1; 2 mi. WNW Lagos de
Moreno, 6370 ft., 19; _2 mi. ESE Tequila_, 4000 ft., 11; _3 mi. W La
Venta_, 33, 1[53]; _12 mi. W Guadalajara_, 3[54]; _Atemajac_, 12[50]; 4 mi.
W Guadalajara, 5100 ft., 3; _2 mi. N, 1/2 mi. W Guadalajara_, 11; 2 mi.
NW Magdalena, 4500 ft., 7[50]; _1 mi. N Tala_, 4400 ft., 3; 3 mi. W Tala,
4300 ft., 18.
_Marginal records._--CHIHUAHUA: Rancho Sanignacio, 4 mi. S, 1 mi. W
Santo Tomas; El Rosario; Balleza. DURANGO: Rosario, 6700 ft.; 1 mi. E
Zarca (Blossom and Burt, 1942:1); 1 mi. N Chorro, 6450 ft. ZACATECAS:
Valparaiso, 6500 ft. AGUASCALIENTES: 1 mi. N Chicalote (Blossom and
Burt, 1942:4). JALISCO: 2 mi. WNW Lagos de Moreno, 6370 ft.; 4 mi. W
Guadalajara, 5100 ft.; 3 mi. W Tala, 4300 ft.; 2 mi. NW Magdalena, 4500
ft. DURANGO: 5 mi. N Durango, 6400 ft.; type locality. CHIHUAHUA: 2 mi.
W Minaca, 6900 ft.
[50] United States National Museum (Biol. Surv. Collections).
[51] American Museum of Natural History.
[52] Univ. Illinois, Mus. Nat. History.
[53] The Museum, Michigan State Univ.
[54] Univ. Michigan, Museum of Zoology.
=Baiomys taylori subater= (V. Bailey)
_Peromyscus taylori subater_, V. Bailey, N. Amer. Fauna, 25:102,
October 24, 1905; Lyon and Osgood, Bull. U. S. Nat. Mus., 62:139,
January 15, 1909; Osgood, N. Amer. Fauna, 28:255, April 17, 1909;
Elliot, Check-List Mamm. N. Amer. Continent, West Indies and
Neighboring Seas, Suppl., Amer. Mus. Nat. Hist, p. 44, January 8,
1917.
_Baiomys taylori subater_, Miller, Bull. U. S. Nat. Mus., 79:136,
December 31, 1912; Miller, Bull. U. S. Nat. Mus., 128:317, April 29,
1924; Anthony, Field Book of North American Mammals, p. 348, 1928;
Baker, Jour. Mamm., 21:223, May 14, 1940; Ellerman, The Families and
Genera of Living Rodents, 2:402, March 21, 1941; Blair, Jour. Mamm.,
22:378, November 14, 1941; Poole and Schantz, Bull. U. S. Nat. Mus.,
178:259, March 6, 1942; Blair, Jour. Mamm., 23:196, May 14, 1942;
Blair and Blossom, Contrib. Lab. Vert. Biol., Univ. Michigan, 40:1,
March, 1948; Miller and Kellogg, Bull. U. S. Nat. Mus., 205:511,
March 3, 1955; Hall and Kelson, The Mammals of North America, 2:659,
March 31, 1959.
_Baiomys taylori_ [= _subater_], Taylor and Davis, Texas Game, Fish
and Oyster Comm. Bull., 27:56, August, 1947 (part).
_Type._--Subadult female, skin and skull; No. 32616/44539 U. S. Nat.
Mus. (Biol. Surv. Coll.); Bernard Creek, near Columbia, Brazoria County,
Texas; obtained on February 25, 1892, by W. Lloyd, original number 1122.
_Range._--Southeastern Texas, north of Matagorda Bay west to Lavaca
County, north to Brazos and Walker counties thence east to Jefferson
County, see Figure 11. Occurs from near sea level in Brazoria and
Galveston counties, up to 500 feet in western part of range. Zonal
range: Humid division of lower Austral (the western part of the
Austroriparian Biotic Province of Dice, 1943:18-21).
_Diagnosis._--Size medium to large for the species; mid-dorsal region
Clove Brown (sooty in freshly captured specimens); some parts of
mid-dorsal region all blackish; individual guard hairs of dorsum
black-tipped, Deep Neutral Gray basally; underfur black-tipped with
subterminal band of light buff, Neutral Gray at base; belly
grayish-white, laterally Isabella Color; distal three-fourths of hairs
in region of throat and chin white, proximal fourth light gray; in
median region of belly distal half of individual hairs white, proximal
half dark gray; vibrissae in most specimens black to base. Average and
extreme cranial measurements of six adults from 7 mi. S La Belle are as
follows: occipitonasal length, 18.9 (17.5-19.4); zygomatic breadth, 9.6
(9.1-9.9); postpalatal length, 6.8 (6.2-7.2); least interorbital
breadth, 3.7 (3.4-3.9); length of incisive foramina, 4.0 (3.6-4.2);
length of rostrum, 6.5 (6.1-6.8); breadth of braincase, 8.7 (8.3-8.9);
depth of cranium, 6.7 (6.6-6.8); alveolar length of maxillary tooth-row,
3.1 (2.9-3.2). Average and extreme external measurements of four adults
from Richmond are as follows: total length, 111.5 (108-118); length of
tail vertebrae, 43.5 (41-47); length of body, 68 (67-71); length of hind
foot, 14 (13-15); for photographs of the skull, see Plate 2_f_, and
Plate 4_g_.