1885.] Geology and Paleontology. 493 
of ramus posterior to P-m. 111 inclusive .106. From the lowest 
beds of the Puerco epoch. D. Baldwin.—Z&. D. Cope. 
MARSUPIALS FROM THE Lower Eocene oF New Mexico.—Two 
families undoubtedly referable to the Marsupialia have been iden- 
tified from the Puerco Eocene, the Polymastodontidæ and Plagi- 
aulacidæ (see NATURALIST, 1884, p. 686, for an account of these 
animals). One genus of each is known, viz., Polymastodon and 
' Ptilodus. I now add a third genus in the Neoplagiaulax of 
Lemoine, which belongs to the Plagiaulacidæ, and has been rep- 
resented hitherto by a single species from the Puerco beds of 
Rheims, France. The American species is very distinct from 
the European, and comes from the base of the formation in New 
Mexico. I describe it as follows : 
.003. D. Baldwin. 
Ptilodus trovessartianus Cope, Report U. S. Geol. Survey Terrs., 
IM, p. 737, Pl. xxv f, Fig. tg—Two mandibles of this species, 
found by Mr. Baldwin, are. in excellent preservation, including 
both the two premolars and the two true molars, and showing 
that the species belongs to Ptilodus rather than to Neoplagiaulax. 
Besides its inferior size, this species differs from the P. med. 
in the smaller second true molar. e tubercles of this tooth 
are two on each side; in the P. medievus they are four on one 
side and two on the other. It comes from the middle horizon of 
the Puerco. aes 
Polymastodon taoénsis Cope: Teniolabis scalper Cope, Report 
S. Geol. Surv. Terrs., UI, p. 193, Pl. Xxiii d, Fig. 7—The 
kind which furnished the typical description of the Teniolabis 
scalper, with superior molars of this genus, and probably of the 
species P, taoénsis, of which several undoubted specimens were 
