986 ‘General Notes, [October, 
formation everywhere. Also by the presence of the genera Læ- 
laps and Diclonius, which in like manner do not extend upwards 
into the Puerco beds. The Lælaps is principally represented by 
teeth, which resemble those of the Z. izcrassatus Cope more than 
those of any other species, although these parts are not alone 
sufficient for the determination of species in this genus. The 
Dysganus agrees with the D. encaustus Cope, which, with the Zæ- 
laps incrassatus, was described from specimens from the Upper 
Missouri. A species of Trionyx and a large crocodile accom- 
pany these species. The latter differs in the character of its teeth 
from any species known to me. The crown is compressed at the 
apex, and there are two well-marked cutting edges, which slope 
in such a way as to divide equal faces unsymmetrically, 2. e., the 
greatest convexity of one not being opposite to that of the other ; 
the transverse section resulting being an oblique oval, or at the 
base a regular oval, with cutting edges at points diagonal to each 
other. On one side of the tooth thus divided, the surface is 
grooved by twenty-five strong sulci, which become very fine at 
the obtuse apex of the tooth. The opposite (external ?) side of 
the crown is smooth, excepting traces of sulci and silky grooving 
towards and at the apex. Diameter of crown where broken off, 
It is thus evident that the Puerco formation is quite distinct 
from the Laramie, although it is possible that it may be proper to 
associate it with the Laramie in the Postcretaceous series.! When 
the Cretaceous mammalian fauna comes to be known, it will be 
very apt to agree with the Puerco in its leading features. These 
are, the absence of Perissodactyla and of Rodentia, and of course 
of mammalian orders not found below the Miocenes ; and in the 
constitution of the mammalian fauna by Condylarthra, Bunothe- 
ria and Marsupialia exclusively. The Postcretaceous series as & 
whole may be ultimately distinguished from the tertiary by these 
peculiarities, together with the presence of the reptilian genus 
Champsosaurus.—Z£. D. Cope. 
This has been done in the table of formations in Vol. 111 U. S. Geol. Survey, F. 
ayden, Tertiary Vertebrata, p. 42. | 
