758 The American Naturalist. [September, 
The extremity of the beak had apparently a horny sheath and was 
adapted for crushing comparatively hard substances. 
AGATHAUMAS Cope—Professor Marsh (Amer. Journ. Sci. Arts, 
1892, p. 83) endeavors to show that this genus differs from any of those 
described by him by quoting characters from my description of the 
type specimen. Since my last description of that genus was published 
(1875), I have studied part of a skeleton obtained by Dr. J. L. 
Wortman in Dakota, of which the parts are undistinguishable from 
those of the Agathawmas silvestre. These include an ilium in much 
better preservation than that of the type, and I am enabled to correct 
some of the statements contained in my original description. I stated 
that there is no facet for the pubis at the front of the acetabulum. 
The surface at this point is broken in both of my specimens, but it is 
altogether probable that the structure at this point does not differ from 
that of the allied forms. The ischiadic suture is in like manner 
obscured by injuries in the type specimen. The Dakota specimen is 
perfectly preserved at this point, and displays a large convex sutural 
surface for the ischium, thus showing that my original description was 
imperfect in this point. The number of sacral vertebre in the original 
specimen is not exactly determinable—only approximately, but this 
region is identical in character with that of other members of the 
family. That the Agathawmas silvestre is one of the largest species of 
the family is indicated by the following measurements of the Dakota 
_ specimen : 
mm. 
PEET T E O TE eday ons RRT 1465 — 
Length of tibia , 940 
‘ pe cae reatest proximal isi 325 
Diameters of tibia s Scat disat n 
anteroposterior oe 
Diameters of dorsal centrum 4 vertical docu ee 
transverse i 137 
The centrum of the dorsal vertebra is slightly opisthoccelous. 
PTEROPELYX Cope—This us was described by me in THE 
AMERICAN Natura.ist for October, 1889 p. 904 (published March 
5th, 1890), It has been subsequently named by Marsh, Claosaurus, in 
the American Journ. Sci. Arts. for May, 1890 (p. 423).—E. D. Cops. 
On a New Genus of Mammalia from the Laramie 
Formation,—In 1881 I had the pleasure of announcing the existence 
of Mammalia in the Laramie formation, and described the new genus 
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