kens and Davis (1957:9) who observed that
dichromatism was correlated with sex. In size, as shown in measurements
below, in darkness of ventral pelage, and in cranial features the
specimens from Sinaloa agree with those from Guerrero, and differ from
specimens of _Artibeus jamaicensis_, in the ways described by Lukens
and Davis (_loc. cit._).

Average measurements of males and females do not differ
significantly. The following are average and extreme
measurements in millimeters of 17 adults (lacking epiphyseal
sutures): total length, 93.4 (90-99); length of hind foot,
19.8 (19-21); length of ear, 23.8 (23-26); length of
forearm, 65.2 (60.1-70.6); greatest length of skull, 29.24
(28.0-30.2); condylocanine length, 25.25 (24.2-26.4);
lambdoidal breadth, 15.92 (15.3-16.6); postorbital
constriction, 6.29 (5.8-6.9); and weight (in grams), 63.2
(51-69).

~Artibeus jamaicensis jamaicensis~ Leach.--A female (61088) obtained on
June 18, 1954, by Albert A. Alcorn, from 32 mi. SSE Culiacan (24 deg.26',
107 deg.07'), Sinaloa, extends the known range of the species approximately
415 miles northwestward from 2 mi. N. Ciudad Guzman (19 deg.43', 103 deg.28'),
Jalisco. Two other females (61089-61090) from central Sinaloa,
collected on June 19, 1954, by A. A. Alcorn, are from 1/2 mi. E Piaxtla
(23 deg.51', 106 deg.38'). Each of the three specimens contained a single
embryo. The embryos (in the order the specimens are listed above)
measured 28, 26, and 25 millimeters. The Sinaloan specimens are both
paler and browner than specimens from Jalisco and from eastern Mexico,
and the facial stripes are more distinct, being as distinct in one
specimen (61088) as in any of the _Artibeus lituratus_ reported here.
Four additional specimens from Jalisco are: 34232-34235, 3 males and 1
nonpregnant female taken by J. R. Alcorn at Hacienda San Martin
(20 deg.18', 103 deg.30'), 18 mi. W Chapala, 5000 feet, on July 12, 1949. Each
specimen of _A. jamaicensis_ listed above lacks epiphyseal sutures and
both an upper and a lower third molar on each side. In size, coloration
of ventral pelage, and configuration of skull, the specimens agree with
the description of specimens from Guerrero and differ from other
species as reported by Lukens and Davis (1957:7, 9).

Minimum and maximum measurements in millimeters for the
three _A. jamaicensis_ from Sinaloa, followed by
corresponding figures for