442 W. B. Scott—Marsupial from the Colorado Miocene. — 
Art. LI.—A new Marsupial from the Miocene of Colorado ; 
by W. B. Scort. 
_ Attuover there can be no reason to doubt that Marsupial 
animals of the opossum type existed in North America during 
Miocene times no remains of them, so far as I am aware, have 
hitherto been found. The Princeton expedition of 1882 ob- 
but very obviously distinct from that species. 
This species may be called Didelphys pygmca, and is defined 
as follows. Opossum very small, intermediate in size between 
D. murina and D. elegans of South America. Lower margit 
of the jaw nearly straight, and the ramus beneath the molar 
teeth of nearly uniform depth; coronoid oe very weak, 
projecting considerably behind the condyle. Molar teeth con- 
structed on the ordinary opossum type, antero-internal cusps 
of penultimate molar very small, and heel of last molar con- 
sisting of two cusps instead of three, as in D. virginiana. 
F.C, A. 
Left ramus mandibuli of D. pygmea, seen Svech the inner side; 4 times the 
natural size, 
This little animal was doubtless an insectivorous opossum, 
some three or four inches long, and finds its nearest living re 
f 
p- 
resentatives in the small insect-eating opossums 0 South , 
America 
‘opportunity to do this. Such opossums probably abounded in 
the sub-tropical Miocene forests of our western territories, 1D 
ile, This 
f 
re 
xs 
we 
