SINCLAIR: MARSUPIALIA OF THE SANTA CRUZ BEDS. 
387 
the Canon de las Vacas (No. 9134, American Museum of Natural History), 
and North Gallegos (No. 15,703). 
Cladosictis lustratus may be readily recognized by the long, narrow, 
depressed skull, with tapering muzzle, moderately expanded arches and 
low inclination forward of the facial profile. The summit line of the long 
sagittal crest is practically horizontal. The anterior superior premolar is 
separated by a short diastema from the canine and by a larger interval 
from the median premolar. The median and posterior premolars are 
almost in contact at the alveolar border. The lower premolars are sep- 
arated from the canine and from each other by diastemata, which vary in 
width considerably in different individuals. The posterior premolar and 
first molar are separated in some specimens by a short interval. 
With the exception of smaller size and less robust build, the skeleton, 
so far as it has been possible to make comparisons, is exactly the same 
as in Cladosictis peter soni, and the description already given in character- 
izing the genus will apply equally to both. 
Within fairly well defined limits, there is considerable individual varia- 
tion in size. This is probably sexual, as the difference between extremes 
is not greater than between the sexes in Thylacynus (cf Thomas, 1888, 
p. 261). The range of this variation is well brought out in the accom- 
panying measurements of the two individuals selected for illustration 
(Nos. 1 5,170 ; 15,046), which are regarded respectively as male and female. 
Measurements. 
No. 15,04.6. 
No. 
Skull, extreme length, premaxillae to lambdoidal crest 
“ width across jugal arches 
“ interorbital width ..... 
Face, length, premaxillae to anterior border of orbit 
Cranium, length to anterior border of orbit . 
“ width at postorbital constriction . 
Nasals, length ....... 
“ width anteriorly ..... 
“ “ posteriorly ..... 
Palate, length ....... 
width between posterior premolars (approximate) 
“ “ “Ml 
Mandible, length ...... 
“ height of coronoid above angle . 
“ transverse diameter of condyle . 
* Slightly decreased by fracture of the angle. 
.142 
.066 approximately 
.022 
.052 
.090 
.010 
.052 
.008 
.024 
.069 
.0125 
.030 
. 1 105 
•039* 
.0152 
I5a7°- 
158 
076 
0258 
0575 
1005 
0115 
.023 
.079 
•015 
•0323 
•1195 
.051 
.0162 
