skull, as reflected in occipitonasal length and zygomatic breadth
relative to length of body, is larger than in other specimens here
assigned to _allex_. The median part of the belly of the eight specimens
is buff-colored rather than whitish-gray as in typical _allex_; the
mid-dorsal region also averages darker than in any other specimens
referred to _allex_. Additional specimens are needed from this and
closely adjacent areas, especially to the west on the coastal plain, in
order to determine more accurately the taxonomic status of the mice
there. At present, it seems best to refer them to _allex_. Possibly the
population represented by the eight specimens is an incipient
subspecies.
There is no evidence of hybridization or intergradation of populations
of _B. t. allex_ with any population of _B. musculus_ where the two
species occur together.
_Specimens examined._--Total 233, all from the Republic of Mexico,
distributed as follows: NAYARIT: 3 mi. SE Mirador, 7; _2 mi. S.
Compostela_, 2900 ft., 5; _4 mi. N Santa Isabel_, 3800 ft., 2[25]; _2 mi.
N Santa Isabel_, 3800 ft., 22[25]; _4 mi SE Ahuacatlan_, 5200 ft., 2[26];
_1 mi. E Ixtlan_, 4000 ft., 13[25]; 1 mi. E Ixtlan del Rio, 3700 ft., 1;
2 mi. WNW Valle de Banderas, near sea level, 1. JALISCO: Arroyo de
Gavalan, 16[28]; Etzatlan, 6[27]; _Mascota_, 3900 ft., 6[27]; _7 mi W
Ameca_, 15[25]; _6 mi. W Ameca_, 15[25]; _3 mi. W Ameca_, 5[25]; Ameca,
4000 ft., 11[27]; _1 mi. SSE Ameca_, 4000 ft., 38; 2 mi. N Resolana, 1500
ft., 28[25]; 13 mi. E, 1 mi. N Talpa de Allende, 8; 2 mi. SSE Autlan, 5;
1 mi. N San Gabriel, 4000 ft., 1[25]; Las Canoas, l[28]. COLIMA: Type
locality, 10[27] (including the type). MICHOACAN: 9 mi. S Lombardia, 1500
ft., 1; _3 mi. W Apatzingan_, 1000 ft, 1; Apatzingan, 3[25]; 10 mi. S, 1
mi. W Apatzingan, 800 ft., 10.
_Marginal records._--NAYARIT: 3 mi. SE Mirador; 1 mi. E Ixtlan del Rio.
JALISCO: Etzatlan; Ameca; 2 mi. N Resolana; Las Canoas. MICHOACAN: 9 mi.
S Lombardia; 10 mi. S, 1 mi. W Apatzingan. COLIMA: type locality.
NAYARIT: Valle de Banderas.
[25] Univ. Michigan, Museum of Zoology.
[26] California Academy of Sciences.
[27] U. S. Nat. Museum (Biol. Surv. Coll.).
[28] American Museum of Natural History.
=Baiomys taylori analogous= (Osgood)
_Peromyscus taylori analogous_ Osgood, N. Amer. Fauna, 28:256,
April 17, 1909 (part); Elliott, Check-List Mamm., N. Amer. Cont.,
West Indies and Neighboring Seas, Suppl., Amer. Mus. Nat. Hist.,
p. 44, January 8, 1917.
_Baiomys taylori analogous_, Miller, Bull. U. S. Nat. Mus., 79:137,
December 31, 1912; Miller, Bull. U. S. Nat. Mus., 128:318, April 29,
1924; Ellerman, The Families and Genera of Living Rodents, British
Mus. Nat. Hist., 2:402, March 21, 1941; Poole and Schantz, Bull.
U. S. Nat. Mus., 178:259, March 6, 1942; Davis, Jour. Mamm., 25:394,
December 12, 1944; Hooper, Jour. Mamm., 28:50, February 15, 1947;
Hall and Villa-R., Univ. Kansas Publs., Mus. Nat. Hist., 1:460,
December 27, 1949; Hall and Villa-R., Anal. del Inst. Biol., 21:196,
September 28, 1950; Goldman, Smith. Miscl. Coll., 114:373, July 31,
1951 (part); Hall and Kelson, Univ. Kansas Publs., Mus. Nat. Hist.,
5:367, December 15, 1952 (part); Villa-R., Anal. del Inst. Biol.,
23:435, May 20, 1953; Miller and Kellogg, Bull. U. S. Nat. Mus.,
205:512, March 3, 1955; Hooper, Occas. Papers Mus. Zool. Univ.
Michigan, 565:13, March 31, 1955; Packard, Proc. Biol. Soc.
Washington, 71:17, April 11, 1958.
_Peromyscus musculus brunneus_, Elliot, Field Columb. Mus. Publ.,
115(8):203, 1907 (part).
_Peromyscus musculus_ [_musculus_], Osgood, N. Amer. Fauna, 28:258,
April 17, 1909 (part).
_Baiomys musculus musculus_, Hall and Villa-R., Univ. Kansas Publs.,
Mus. Nat. Hist., 1:460, December 27, 1949 (part); Hall and Villa-R.,
Anal. del Inst. Biol., 21:196, September 28, 1950 (part).
_Baiomys taylori taylori_, Dalquest, Louisiana State Univ. Studies
(Biol. Sci. Ser.), 1:155, December 28, 1953 (part); Hall and Kelson,
The Mammals of North America, 2:660, March 31, 1959 (part).
_Baiomys taylori allex_, Hall and Kelson, The Mammals of North
America, 2:659, March 31, 1959 (part).
_Baiomys musculus musculus_, Hall and Kelson, The Mammals of North
America, 2:661, March 31, 1959 (part).
_Type._--Adult male, skin and skull; No. 120261 U. S. Nat. Mus. (Biol.
Surv. Coll.); Zamora, Michoacan, Republic of Mexico, obtained on January
15, 1903, by E. W. Nelson, and E. A. Goldman, original number 15764.
_Range._--Central and eastern Jalisco south into Michoacan, east through
Guanajuato, Queretaro, thence into Estado Mexico, and Distrito Federal,
and west-central Veracruz, see Figure 11. Zonal range: approximately the
Transverse Volcanic Biotic Province of Moore (1945:218) and of Goldman
and Moore (1945:349). Occurs from 5000 feet, 7 mi. S Ocotlan, Jalisco,
up to 8000 feet in Ixtapalapa, Distrito Federal.
_Diagnosis._--Size large for the species; dorsum dark Sepia to near
blackish medially in freshly taken specimens (Sepia fading to near
Fuscous in prepared specimens); belly slaty-gray, hairs Deep Neutral
Gray near tips and Dusky Neutral Gray at bases; hairs on back
black-tipped with subterminal band of Ochraceous-Tawny (guard hairs
blackish to base); hairs of throat and chin white-tipped, gray at bases;
dorsal vibrissae black, ventral and anteriormost vibrissae white; hairs
on face and sides black-tipped, and Ochraceous-Tawny at base; ears
sparsely haired, individual hairs grayish, blackish, and ochraceous;
tail sooty to blackish dorsally, lighter ventrally; forefeet and hind
feet sooty brown on dorsal and ventral surface. Skull relatively broad
interorbitally; zygoma broad and squared; cranium larger in all
dimensions than in most other subspecies. Average and extreme
measurements of 10 adults from 1 mi. S, 11 mi. W Zamora, 5400 ft.,
Michoacan, are: total length, 109.4 (102-121); length of body, 64.3
(58-72); length of tail, 44.9 (39-51); length of hind foot, 14.6
(14-15); occipitonasal length, 18.0 (17.5-18.6); zygomatic breadth, 9.4
(9.1-9.7); postpalatal length, 6.6 (6.2-7.2); least interorbital
breadth, 3.5 (3.3-3.8); length of incisive foramina, 4.0 (3.8-4.2);
length of rostrum, 6.2 (5.8-6.5); breadth of braincase, 8.7 (8.5-8.9);
depth of cranium, 6.6 (6.3-6.9); alveolar length of maxillary tooth-row,
3.1 (3.0-3.3); for photographs of skull, see Plate 2_a_ and Plate 4_b_.
_Comparisons._--For comparisons with _B. t. allex_, _B. t. canutus_, _B.
t. paulus_, and _B. t. fuliginatus_, see accounts of those subspecies.
From _B. t. taylori_, _B. t. analogous_ differs as follows: sides and
dorsum darker, differing most in freshly prepared specimens; dorsal
surface of forefeet and hind feet darker; basal part of hairs on belly
darker gray; frontal bones less constricted, causing less taper
anteriorly in interorbital space; interparietal wider transversely;
basioccipital more expanded laterally, narrowing more abruptly at suture
between basioccipital and basisphenoid.
_Remarks._--The pelage of _analogous_ becomes paler with wear as pointed
out by Osgood (1909:257). A paratype, U. S. Nat. Mus. 120260, and
several specimens from 1 mi. S, 11 mi. W Zamora, Michoacan, are grayish
rather than brownish-black. All of these are old adults having the
terminal black parts of the hairs on the dorsum nearly worn away.
Excluding such grayish individuals, _B. t. analogous_, like _B. t.
subater_ and _B. t. fuliginatus_, is uniformly brownish-black. Both
_analogous_ and _fuliginatus_ occur in relatively high mountainous
country on dark soils or pedregals, and all three of the aforementioned
subspecies occur in zones of high relative humidity.
_B. t. analogous_ intergrades with _B. t. paulus_ (see account of that
subspecies) and _B. t. allex_ south and west of Lago de Chapala in
Jalisco. Additional specimens are needed from Queretaro and San Luis
Potosi in order to ascertain whether or not _B. t. analogous_
intergrades with _B. t. fuliginatus_ or _B. t. taylori_. Specimens from
western Jalisco, in the past referred to _B. t. analogous_, are
referable to _B. t. allex_ (see account of that subspecies). Specimens
obtained west of, and bordering, the Rio del Naranjo in Jalisco show a
mixture of characters of both _B. t. allex_ and _B. t. analogous_. For
example, specimens from 2 mi. N Ciudad Guzman resemble _analogous_ on
the dorsum, whereas, on the belly, the individual hairs are
white-tipped, pale gray at the base, and in over-all appearance are
whitish-gray, unlike typical _analogous_ (being like _allex_ instead).
The dorsal surface of the forefeet are sooty to light brownish (as in
_analogous_), whereas, the hind feet are flesh-colored (as in _allex_).
Another series of specimens from 4 mi. W Leon, Guanajuato, are
intergrades between _B. t. analogous_ and _B. t. paulus_. These
specimens are grayish to brownish on the dorsum, have sooty forefeet and
hind feet (more nearly as in _analogous_ than in _paulus_), are
grayish-white on the venter, and have a distinctly bicolored tail
(resembling that of _paulus_ more than that of _analogous_). When the
average of cranial characters is considered, both series are best
referred to _analogous_.
Hooper (1947:50) pointed out that specimens from the pedregal San
Geronimo, Distrito Federal, were more nearly black than topotypes and
generally showed less brownish hues typical of _analogous_. I have
examined this series and several others from this area (see Specimens
examined, p. 640) and am convinced that these populations average
darker. Actually, the dorsum is more nearly black and the venter is more
buffy than in typical _analogous_. The hairs of these individuals
average longer than in other populations of _analogous_. Skulls of the
specimens from the pedregal are indistinguishable from those of
paratypes of _analogous_. The populations from the Distrito Federal seem
to be incipient subspecies.
_Specimens examined._--Total 696, all from the Republic of Mexico,
distributed as follows: SAN LUIS POTOSI: Hacienda Capulin, 5[33]; _3.3
mi. N Tamazunchale, by-road_, 2[34]; 1 mi. N Tamazunchale, 700 ft., 1[35].
VERACRUZ: Acultzingo, 4[29], 1[31]. JALISCO: 1 mi. S Jalostotitlan, 5700
ft., 5; 7 mi. NW Tepatitlan, 3[29]; _6 mi. N, 4 mi. E Tepatitlan_, 6400
ft., 25; _2-1/2 mi. E Tepatitlan_, 6200 ft., 15; _2 mi. S, 1/2 mi. W
Tepatitlan_, 9; _near Tepatitlan_, 2; _5 mi. SW Arrandas_, 6700 ft., 6;
_2 mi. E Zapotlanejo_, 23; _2-1/2 mi. E Puente Grande_ (_5-1/2 mi. SW
Zapotlanejo_), 3; _8 mi. S Guadalajara_, 10[29]; _3 mi. ENE Santa Cruz de
las Flores_, 9; _4 mi. NE Ocotlan_, 5050 ft., 18; _13 mi. S, 9-1/2 mi. W
Guadalajara_, 1; _2 mi. WNW Ocotlan_, 5000 ft., 15; 13 mi. S, 15 mi. W
Guadalajara, 2; _Ocotlan_, 5000 ft., 8[30]; _1 mi. S Ocotlan_, 5000 ft.,
12; 27 mi. S, 12 mi. W Guadalajara, 9; _1-1/2 mi. N Mazatmitla_, 6[29];
_1/2 mi. NW Mazatmitla_, 4; _3 mi. WSW Mazatmitla_, 4; 2 mi. N Ciudad
Guzman, 5000 ft., 18. GUANAJUATO: 4 mi. N, 5 mi. W Leon, 7000 ft., 25; 5
mi. S Salamanca, 2[29]; _5 mi. E Celaya_, 6000 ft., 6; _1 mi. E Yuriria_,
5725 ft., 3; Salvatierra, 5775 ft., 8; _NE edge Acambaro_, 6050 ft., 10;
_Acambaro_, 3[30]. QUERETARO: Toliman, 7[30]; 6 mi. E Queretaro, 6550 ft.,
37. HIDALGO: Tula, 2050 m., 1[31]. MICHOACAN: _2 mi. E La Palma, SE side
Lago de Chapala_, 7; type locality, 4000 ft., 10[30] (including the
type); _9 mi. E Zamora_ (_Camenaro_), 2[29]; _1 mi. S, 11 mi. W Zamora_,
5400 ft., 17; S Cuitzeo, 36[29]; _Jiquilpan_, 4800 ft., 15; _11 mi. W
Jiquilpan_, 6700 ft., 2; _1 mi. E Jiquilpan_, 7; _1 mi. E Zinapecuaro_,
6300 ft., 17; _4-1/2 mi. NE Tarequato_ (_Tarecuato_), 6600 ft, 1;
_Tanganciguaro_ (_Tangancicuaro_), 5500 ft., 4; _2 mi. N Tarecuato_,
7200 ft., 1; _2 mi. S Maravatio_, 6650 ft, 6; _2 mi. SE Zacapu_, 6600
ft., 11; _1 mi. N Tinquindin_ (_Tinguindin_), 6300 ft., 2; _3 mi. E
Morelia_, 6600 ft., 3; _11 mi. E, 2 mi. S Morelia_, 1; 2 mi. SE Hidalgo
(Villa Hidalgo), 6; _1-1/2 mi. N Los Reyes_, 1; _E Los Reyes_, 18[29];
_Los Reyes_, 8[30]; _3 mi. W, 1 mi. N Patzucuaro_, 6600 ft., 2; _N
Patzucuaro_, 2[29]; _Patzucuaro_ 9[31], 4[30], 4[29]; Uruapan, 1[29]; _E
Uruapan_, 12; _2-1/2 mi. E Uruapan_ (_La Presca_), 2[29]; 2 mi. SW
Zitacuaro, 1; 1 mi. E, 6 mi. S Tacambaro, 4000 ft., 11[37]; _La Huacana_,
1[30]. MEXICO: Templo del Sol, Pyramides de San Juan, Teotihuacan, 8000
ft., 1; _31 km. E Mexico City_, 7500 ft., 11[36]; _17 km. E Mexico City_,
7500 ft, 1[36]; _Cerro La Caldera, 11 mi. ESE Mexico_, 2350 m., 5; 4 km.
ENE Tlalmanalco, 2290 m., 9; _Hacienda Cordoba_ (_Cordova_), 6. MEXICO,
D. F.: _Cerro de la Estrella, Ixtapalapa_, 2450 m., 1; _3/4 mi. S, 1 mi.
E Churubusco_, 2400 m., 2; _5 km. S Mexico City, South of Cd.
Universitaria_, l[32]; _Pedregal San Angel_, _2.6 mi. S Monumento a
Obregon, 2_; _El Pedregal, 1 km. S San Angel_, 2260 m., 1; _Falda SW
Cerro Zacatepec, 3.9 mi. SW Monumento a Obregon_, 1; _2 mi. N Tlalpan,
Zacayuca_, 2380 m., 5; _Tlalpan_ (_Pedregal_), 2400 m., 21[31]; _San
Geronimo_, 37[29], 6[38]; _Santa Rosa_, 2700 m., 1[32]; _Tlalpan_, 8; _3/4
mi. SW Las Fuentes, Tlalpan_, 2450 m., 25[30]; _Tepepan_, 6[29]; _Rancho
La Noria, 1 mi. W Xochimilco_, 2270 m., 4; _500 meters N Xochitepec_,
2250 m., 7; 200 m. N San Mateo Xalpa (Jalpa), 2390 m., 2.
_Marginal records._--SAN LUIS POTOSI: Hacienda Capulin; 1 mi. N
Tamazunchale. HIDALGO: Tula, 2050 m. MEXICO: Templo del Sol, Pyramides
de San Juan, Teotihuacan. VERACRUZ: Acultzingo. MEXICO: 4 km. ENE
Tlalmanalco. MEXICO, D. F.: 200 m. N San Mateo Xalpa (Jalpa), 2390 m.
MICHOACAN: 2 mi. SW Zitacuaro; 1 mi. E, 6 mi. S Tacambaro; Uruapan.
JALISCO: 2 mi. N Ciudad Guzman; 27 mi. S, 12 mi. W Guadalajara; 13 mi.
S, 15 mi. W Guadalajara; 7 mi. NW Tepatitlan; 1 mi. S Jalostotitlan,
5700 ft. GUANAJUATO: 4 mi. N, 5 mi. W Leon. QUERETARO: 6 mi. E
Queretaro, 6550 ft.; Toliman.
[29] Univ. Michigan, Museum of Zoology.
[30] U. S. Nat. Museum (Biol. Surv. Coll.).
[31] Chicago Natural History Museum.
[32] American Museum of Natural History.
[33] Museum of Natural History, Louisiana State University.
[34] Univ. Illinois, Mus. Nat. History.
[35] The Museum, Michigan State Univ.
[36] Texas A & M, Cooperative Wildlife Research Collection.
[37] Univ. California, Mus. Vert. Zoology.
[38] University of Florida Collections.
=Baiomys taylori ater= (Blossom and Burt)
_Baiomys taylori ater_ Blossom and Burt, Occas. Papers Mus. Zool.,
Univ. Michigan, 465:2, October 8, 1942; Blair and Blossom, Contrib.
Lab. Vert. Biol., Univ. Michigan, 40:1, March, 1948; Hoffmeister and
Goodpaster, Ill. Biol. Monogr., 24(1):115, December 31, 1954; Miller
and Kellogg, Bull. U. S. Nat. Mus., 205:511, March 3, 1955;
Hoffmeister, Amer. Midland Nat., 55:281, April, 1956; Packard, Jour.
Mamm., 40:146, February 20, 1959; Hall and Kelson, The Mammals of
North America, 2:659, March 31, 1959 (part).
_Peromyscus taylori paulus_, Osgood, N. Amer. Fauna, 28:256, April
17, 1909 (part).
_Baiomys taylori_ [_ater_], Justice, Jour. Mamm., 38:520, November
20, 1957.
_Type._--Adult male, skin and skull; No. 85425, University of Michigan,
Museum of Zoology; 7 mi. W Hereford, Cochise County, Arizona, obtained
on March 25, 1941, by Philip M. Blossom, original number 2195.
_Range._--Southeastern Arizona, north to Graham County, thence east to
the Animas Valley, Hidalgo County, New Mexico; south to northern
Chihuahua and northwest to the southern border of Cochise County,
Arizona, see Figure 11. Zonal range: largely lower Sonoran (Apachian
Biotic Province of Dice, 1943:56). Occurs from 4300 feet in Chihuahua up
to 6200 feet in New Mexico.
_Diagnosis._--Size medium for the species; dorsum between Mummy Brown
and Prouts Brown; individual tips of hairs intermixture of black and
Ochraceous-Tawny, bases of all hairs slate-gray; sides of body and face,
Buffy Brown to Cinnamon Brown; belly Cinnamon Buff, proximal half of
individual hairs Deep Neutral Gray, distal half white; in region of
throat, proximal fourth of individual hairs gray, distal three-fourths
white; dorsal vibrissae black to base, ventral vibrissae white to base;
tail brownish above, gray below; dorsal and ventral surface of forefeet
and hind feet buffy to gray; interparietal somewhat compressed
anteroposteriorly. Average and extreme cranial measurements of 15 adults
from 9-1/2 mi. W New Mexico State Line, 5-1/2 mi. N Mexican border,
Cochise County, Arizona, are as follows: occipitonasal length, 18.0
(17.5-18.6); zygomatic breadth, 9.5 (9.2-9.9); postpalatal length, 6.6
(6.0-7.1); least interorbital breadth, 3.6 (3.4-3.8); length of incisive
foramina, 4.0 (3.8-4.2); length of rostrum, 6.1 (5.7-6.4); breadth of
braincase, 8.6 (8.4-9.1); depth of cranium, 6.5 (6.3-6.9); alveolar
length of maxillary tooth-row, 3.2 (3.1-3.4). Average and extreme
external measurements for six adults from 9 mi. W Hereford, Cochise
County, are as follows: total length, 106.3 (98-115); length of tail
vertebrae, 42.3 (39-46); length of body, 64 (59-69); length of hind
foot, 13.6 (13-14.2); length of ear from notch, 11.1 (10.5-11.5); for
photographs of skull, see Plate 2_b_, and Plate 4_c_.
_Comparisons._--For comparisons with _B. t. canutus_, see account of
that subspecies. From _B. t. paulus_, the subspecies to the southeast,
_B. t. ater_ differs in: dorsum darker brown; tail less strikingly
bicolored; belly buffy rather than whitish to white-gray; forefeet and
hind feet darker dorsally and ventrally; posterior margin of
basioccipital bowed anteriorly in a broad U-shape with a secondary small
median anteriorly directed U-shaped curve, rather than bowed anteriorly
in a simple U-shape; interparietal more compressed anteroposteriorly;
coronoid process of mandible so acutely recurved that tip of coronoid
points posteroventrally and appears sickle-shaped.
_Remarks._--Blossom and Burt (1942:1) described _B. t. ater_ as the
darkest of the known subspecies. It is dark, but specimens from some
parts of the ranges of _B. t. analogous_, _B. t. fuliginatus_, and _B.
t. subater_ exceed in melanins the darkest individuals of _ater_. Blair
and Blossom (1948:5) also concluded by the use of an Ives tint
photometer that _B. t. subater_ was significantly darker than _B. t.
ater_.
When paratypes of _ater_ and specimens of _B. t. paulus_ are compared,
the darkest individuals of _ater_ exceed but slightly the darkest of
_paulus_. The darkest specimens of _paulus_ occur in southern Zacatecas,
and northern Jalisco, and the palest of the series are in northern
Durango and southern Chihuahua. When paratypes of _ater_ and _paulus_
are compared, the difference in color is readily distinguishable.
Specimens from 1-1/2 mi. N San Francisco, in northern Chihuahua, appear
to be intermediate in color between _ater_ and _paulus_ except for a
faint tinge of buff ventrally. In characters of the crania, these
specimens resemble _ater_ and are referred to that subspecies. A
slightly different pattern of color is present in pygmy mice from the
Peloncillo Mountains and the Animas Valley of New Mexico; the upper
parts resemble those of paratypes of _ater_, but the venter has only the
faintest suggestion of the buffy wash. Crania of these specimens from
New Mexico are inseparable from those of paratypes of _ater_, and the
specimens are, therefore, referred to _ater_.
When specimens are arranged by localities from Arizona east into
southern New Mexico, thence south into Chihuahua and Durango, gradual
intergradation in color is evident from dark in the north to pale browns
in the south, whereas, size and shape of interparietal and size and
shape of coronoid process of the lower jaw divide quite distinctly into
two morphological types in central Chihuahua.
Cranial variation in size and proportion among adults is slight
throughout the range of _ater_ compared to variation detected in other
subspecies of _Baiomys taylori_. Perhaps such a relatively stable
pattern of characters of the crania reflects the homogeneity of the gene
pool, with respect to these characters, of the populations sampled. The
fact that the color of the pelage of this subspecies varies considerable
throughout its known range and that the crania do not is perhaps a clue
to the mode of inheritance of characters in these mice. Seemingly, color
of pelage is inherited independently of characters of the cranium. The
relative lack of variability in the crania of _ater_ may result from
uniform environmental conditions, which have served to select for
uniform characters in the populations. All of the other wide-ranging
subspecies of _B. taylori_ occupy more diverse habitats than _ater_.
Secondly, the rather abrupt change in the cline of measured characters
of the crania between _ater_ and _paulus_ in central Chihuahua suggests
a secondary zone of intergradation. The probable cessation of gene flow
in the past between these two subspecies, allowing _ater_ to be isolated
for a time, may also, in part, account for the relative lack of
variability in the crania of _ater_.
_Specimens examined._--Total 58, distributed as follows: ARIZONA:
_Graham County_: 1-1/2 mi. SW Ft. Grant, Graham Mts., 1[39]; _Pima
County_: 1-1/2 mi. ENE Greaterville, Thurber Ranch, 2[39]; _Santa Cruz
County_: Patagonia, 3[39]; _Cochise County_: _9 mi. W Hereford_, 10[43];
type locality, 2[43] (including the type); _5 mi. W Hereford_, 5[43];
9-1/2 mi. W New Mexico State Line, 5-1/2 mi. N Mexican border, 20[42]; _3
mi. E, 1 mi. N Chiricahua_, 1[42]. NEW MEXICO: _Hidalgo County_: 18 mi.
S, 2 mi. W Animas, 2; _22 mi. S, 2 mi. W Rodeo_, 6000 ft., 1[40]; _22 mi.
S, 2 mi. E Rodeo_, 6000 ft., 3[40]; 25-1/2 mi. S Animas, 6200 ft. (in Big
Bill Canyon), 1[40]. CHIHUAHUA: _5-1/2 mi. N, 2 mi. W San Francisco_,
5100 ft., 1; _2-1/2 mi. N, 3 mi. W San Francisco_, 5200 ft., 1; 1-1/2
mi. N San Francisco, 5100 ft., 4; Casas Grandes, 4300 ft., 1[41].
_Marginal records_--ARIZONA: 1-1/2 mi. SW Ft. Grant, Graham Mts. NEW
MEXICO: 18 mi. S, 2 mi. W Animas; 25-1/2 mi. S Animas (in Big Bill
Canyon). CHIHUAHUA: 1-1/2 mi. N San Francisco; Casas Grandes. ARIZONA:
Patagonia; 1-1/2 mi. ENE Greaterville, Thurber Ranch.
[39] University of Illinois, Museum of Natural History.
[40] University of New Mexico.
[41] U. S. Nat. Museum (Biol. Surv. Coll.).
[42] University of Arizona.
[43] Univ. Michigan, Museum of Zoology.
=Baiomys taylori canutus=, new subspecies
_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_, Miller, Bull. U. S. Nat. Mus., 79:137,
December 31, 1912 (part); Miller, Bull. U. S. Nat. Mus., 128:317,
April 29, 1924 (part); Burt, Miscl. Publ., Mus. Zool., Univ.
Michigan, 39:54, February 14, 1938; Goldman, Smith. Miscl. Coll.,
115:373, July 31, 1951 (part); Miller and Kellogg, Bull. U. S. Nat.
Mus., 205:512, March 3, 1955 (part); Hooper, Occas. Papers Mus.
Zool., Univ. Michigan, 565:13, March 31, 1955; Hall and Kelson, The
Mammals of North America, 2:659, March 31, 1959 (part).
_Baiomys musculus musculus_, Goldman, Smith. Miscl. Coll., 115:336,
July 31, 1951 (part).
_Type._--Adult male, skin and skull; No. 62075, University of Kansas,
Museum of Natural History; 1 mi. S Pericos, Sinaloa, Republic of Mexico;
obtained on June 14, 1954, by A. A. Alcorn, original number 1754.
_Range._--Central Nayarit northward through western Sinaloa, to as far
north as south-central Sonora, see Figure 11. Zonal range: Lower arid
tropical, closely approximating the Sinaloan Biotic Province of Goldman
and Moore (1945:349). Occurs from near sea level at Escuinapa (43 feet),
Sinaloa, to 3200 feet at a place 2 mi. WNW Tepic, Nayarit.