1879.] Geology and Paleontology. 333 
a large tail; it was termed Pleuronura pellati. The third type 
was represented by a humerus which resembles that of the Dime- 
trodon of Texas, and similar forms from the Ural and South Af- 
rica, in presenting some Mammalian features. He referred it to 
a new genus, under the name of Zuchyrosaurus, which is probably 
Pelycosaurian. 
A Stine Ray FROM THE GREEN RIVER SHALES OF WYOMING.— 
Leslie A. Lee, of Bowdoin College, Me., recently lent me for exam- 
ination an interesting fossil from the ‘above formation, from the 
locality which has recently furnished such fine specimens of 
Mioplosus, Diplomystus, etc. It is a species of sting ray nearly 
allied to the genus Z7rygon, but so far different as to be referable 
to another genus which I propose to name Aiphotrygon. Its 
characters are: teeth with produced triangular crowns as in Raja. 
Caudal spines compressed, with a single serrate-edge, which is 
dorsal. No caudal fins discoverable. The species has a rather 
long acuminate snout without superficial ossification, from whose 
apex the pectoral fin borders diverge. The latter do not extend pos- 
terior to the ventrals. Tail very long and slender, nearly twice as 
long as head and abdomen. Caudal spines (three present in the 
Specimen) with a shallow lateral Pete but otherwise smooth. 
Pectoral rays 314104 41. Tot tal | ength m 515; width at 
middle of abdomen .230; length of head 100; Joti of tail 
-351; length of spine .040. The species may = ‘called Aiphotry- 
gon acutidens. The Zrygon muricata, of Monte Bolca, has the 
typical form of spine, according to Gazzola ae, D. Cope. 
AMERICAN ACERATHERIA.—Four species of rhinoceroses have 
been found within the limits of the United States, which may be 
referred to the above genus. They are, commencing with | the 
smallest, A. mite Cope, A. occidentale Leidy, A. pacificum Leidy 
s the lar 
csi megalodus of the Loup River formation. It is only 
known from an incomplete mandible, which supports molar, 
canine si incisor teeth. The former have the usual form. The 
crowns of the canines are considerably wider than those of the 
incisors, but do not project very far beyond them. They are sub- 
triangular i in outline, having a prominent shoulder at the base on 
the inner side. There is but one incisor on each side, which has 
a transverse crown. Diastema long; ascending ramus vertical, 
flat in front. Depth of ramus at last molar. 065 ; length of last 
molar .045; width of do. .029; length of crown of canine .027; 
width do. at base .02 
From beds of the Truckee epoch of the White River forma- 
tion. This name, introduced by King, has priority of publication 
over the term Oregon beds introduced by me, hence the latter 
must be abandoned. 
