No. 5.— Preliminary Account of the Fossil Mammals from the 
White River Formation contained in the Museum of Comparative 
Zoology. By W. B. Scorr anp Henry F. Osporn. 
Tus paper is a brief abstract of a memoir upon the Cambridge col- 
lection of Miocene Mammals, which is now in preparation. This 
collection was made by Mr. Samuel Garman in Nebraska and Dakota, 
and has been very kindly placed in our hands by Professor Agassiz for 
preparation and description. The work of excavating, cleaning, and 
mounting the fossils has been for the most part performed by Dr. 
Franklin C. Hill, Curator of the Geological Museum at Princeton, and 
to him our best thanks are due. The drawings were all executed by Mr. 
R. Weber. 
GEOLOGICAL MusEum, Princeton, N. J., July 9, 1887. 
RODENTIA. 
Paleolagus Haydeni, Leidy. Several specimens of jaws and teeth repre- 
sent this species in the collection, but add nothing to our previous knowledge. 
Ischyromys typus, Leidy. Isolated teeth. 
CREODONTA. 
Hyznodon horridus, Leidy. A most valuable and indeed unique speci- 
men of this species, belonging to the Cambridge collection, has already been 
described by one of us elsewhere.* Here it will suffice to recapitulate some of 
the more important facts established by it. The posterior dorsal and lumbar 
vertebrae show the characteristically creodont feature of involuted zygapophy- 
~ ses, such as are not found in any known carnivore. The scaphoid and lunar 
bones are separate, and a distinct central is found; the manus is plantigrade 
and pentadactyl, and the ungual phalanges are deeply cleft. This specimen 
renders it perfectly certain that Hyenodon was a typical creodont, and that it 
was in all probability an aquatic form. It also shows that Hyenodon is not at 
all allied to Mesonyzx, as has been supposed, but rather to Pterodon, Protopsalis, 
and Oxyena. 
* Scott, Journ. Acad. Nat. Sci. Phil., Ser. 2, Vol. IX. No. 2. 
VOL XIII. —wno. 5. 
