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The other premolars and the molars are much alike in the two genera save that the latter are relatively broader in Merycodesmus. This genus differ from Leptotragulus in the greater complexity of the inferior premolars, and especially in the large development of the deuteroconid on P . From Oromeryx it may be distinguished by the diastemata and by the more symmetrically quadrate shape of the upper molars.

The skull bears a close resemblance to that of Parameryx, but has a somewhat more elongate muzzle and longer postorbital processes of the frontals; the forehead has the same elongate lozengelike shape, the temporal ridges converging gradually behind into the short sagittal crest; the mandible has an elongate, slender horizontal ramus, which is somewhat stouter than that of Parameryx ; whether the very broad ascending ramus possessed a similar hooklike angle to that of the latter genus cannot at present be precisely determined; the coronoid process is even more recurved and pointed. The posterior nares are far back, their front border being opposite m *, and a deep palatal notch intervenes between the hinder half of m 3 and the external wall of the narial canal.

The axis has a conical odontoid process.

The fore foot has four digits, of which the lateral metacarpals are reduced and slender, though distinctly less so than in Parameryx. The tarsus is lower than in the latter genus, and the lateral metatarsals are functional, not mere filiform splints. The phalanges are essentially alike in the two genera.

The entire structure of Merycodesmus strongly suggests that it was the forerunner of the White River genus, Leptomeryx, and, through a somewhat different line, of Protoceras also.

In Leptomeryx the upper canines have been lost, the lower canine resembles an incisor, but p 1 is just like a minute canine and one can hardly escape the inference that it formerly functioned as a canine and has dwindled because of the loss of the upper canine, which it opposed. Protoceras still retains, in the male sex, the large upper canine, which is opposed by p. 1 and thus abraded upon the posterior surface, but in the females the upper canine is vestigial.

CAMELOMERYx, gen. nov.

I.2, C. 1, P.4, M. 3. Upper incisors small, canines stout, but short; a long diastema between p 1 and p 2. Premolars and molars closely

resembling those of the preceding genus, but molars with larger external buttresses. Forehead broad and short, sagittal crest long; temporal ridges confined to frontals. Posterior nares farther back than in Merycodesmus and palatal notches absent.

In this genus the superior dentition is, except in the character of the incisors, very similar to that of Merycodesmus, but the shape of the forehead, the cranium and the hinder part of the palate are very different. In the absence of the lower jaw, it is not practicable to determine finally whether this form is congeneric with Leptotragulus, but the character of the upper premolars leads me to believe that it will prove to be quite distinct.

Camelomeryx longiceps, sp. nov. Size, small; cranium long and slender ; orbits small and widely open behind; postorbital processes of frontals extended transversely, but little decurved.

Measurements.

Upper dentition, length I i to M 3

canine, ant.-post. diameter
canine, transverse diameter
premolar-molar series, length..
premolar series, length .
molar series, length....
M 1, length....
M 1, width.
M 2, length.
M 2, width..
M 3, length..
M 3, width.

....0.062

.005 .003 .051 .029 .021 .0055 .0075 .007 .OIO .0085 .0115

That Camelomeryx and Merycodesmus are nearly allied genera will be at once apparent from the foregoing description. Whether the former is the ancestor of some White River genus, such as Hypertragulus, or whether it is a mere variant of Merycodesmus and without permanent phylogenetic significance, must await the decision of more complete material.

OROMERYX Marsh.

Oromeryx Marsh, Amer. Journ. Sci., third series, Vol. xiv, p.

364 (nomen nudum).

Oromeryx Marsh, Amer. Journ. Sci., third series, Vol. xlviii,

p. 269.

No representative of this genus has yet been detected in the Princeton collection ; it may be distinguished from the preceding genera by two principal characters. According to Marsh, “there is no diastema in the dentition," and in the second place, his figure shows that the upper molars, especially m 3, have a subovate crown, due to the much greater transverse breadth in the anterior than in the posterior half.

PROTOREODON Scott and Osborn.

Agriochærus Marsh (non Leidy), Amer. Journ. Sci., third series,

Vol. ix, p. 250. Eomeryx Marsh, ibid., Vol. xiv, p. 364 (nomen nudum). Protoreodon Scott and Osborn, Proc. AMER. Phil. Soc., 1887,

p. 257. Eomeryx Marsh, Amer. Journ. Sci., third series, Vol. xlviii, p. 266.

The collection contains a large number of specimens appertaining to this genus, and adds very materially to our knowledge of it, but as the newly acquired individuals only confirm the conclusion previously reached, that this genus is ancestral to the Oreodontida of the Oligocene and Miocene, description of the new material will be reserved for the extended paper.

AGRIOTHERIUM gen. nov.

Premaxillaries reduced and upper incisors small; upper canine large, recurved and trihedral ; premolars simple and thick transversely; P i caniniform ; p 3 implanted by three fangs, but has no deuterocone; deuterocone of p 4 conical, not crescentic; molars like those of Protoreodon, but with outer crescents of superior molars more concave, and more prominent median buttress, into which median valley extends. Cranium relatively longer and face shorter than in Protorcodon and postorbital processes of frontals shorter.

This genus is evidently very close to Protoreodon, but may be distinguished from it by the reduced premaxillaries, the smaller incisors, the simpler premolars and the more concave outer lobes of the upper molars, as well as by the longer cranium, shorter face, and less prominent postorbital processes.

Agriotherium paradoxicum, sp. nov. Skull about equal to that of Oreodon gracilis in length, but much more depressed; mandible stout and chin steeply inclined.

Measurements.

Skull, length on basal line....

width across zygomata. .
Length occ. crest to ant. border of orbit..

ant. border orbit to prmx.
Mandible, height of condyle..

depth at m., ..
Upper premolar-molar series, length.

premolar series, length
molar series, length....
canine, ant.-post. diameter.
canine, transverse diameter..
Pi, length..
P 2, length.
P 3, length
3,

width...
P 4, length..
P 4, width.
M 1, length..

width.
M. 2, length.
M 2, width...
M 3, length.
3,

width.
Lower P 3, length

P
3,

width..
P 4, length.
P 4, width.....
molar series, length.
M 1, length

width..
M 2, length.
M 2, width.
M 3, length..
M
3,

width...

.0.131

.077 .085 .051 .048 .025 .0525 .029 .024 .006 .006 .0075 .0065 .007 .006 .006 .0085 .075 .009 .008

P

MI,

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M

.01 2

.007 .003 .0075 .004 .027 .007 .0055 .008 .006

MI,

.012

.007

The differences between Protoreodon and Agriotherium are such as strongly to suggest the inference that, while the former is the ancestor of the Oreodonts, the latter stands in a similar relation to the Agriocheerids. This determination can, at present, be only provisional, until more is learned concerning the foot-structure of the present genus. At all events, if Agriotherium be not the desired ancestral form, we may feel confident that that form, when found, will prove to be of a very similar character.

HYOMERYX Marsh.

Amer. Journ. Sci., third series, Vol. xlviii, p. 268.

This genus, which is described as having no upper incisors, I have not seen.

It differs from the two preceding genera not only in the loss of the upper incisors, but also in the form of the upper molars, which have far less concave external crescents, and less prominent outer buttresses.

The study of the Uinta Selenodonts lends much strength to the opinion expressed by various writers, that the Oreodonts are related to the Tylopoda. It now appears likely that this family leads back either to Homacodon of the Bridger, or to some nearly allied form of the same family. If this be true, we shall then have the more extended generalization, that all of the indigenous North American Selenodonts belonged to the Tylopoda and that this suborder has had a much more extended and varied development than we have hitherto supposed. While this conclusion is already extremely probable for the other families, we have yet to find the direct forerunners of Protoreodon and Agriotherium before it can be established for the Oreodonts and Agriocherids.

Stated Meeting, April 1, 1898.
Mr. FREDERICK PRIME in the Chair.

Present, 12 members.

Correspondence was submitted and donations reported.

Dr. Morris, on behalf of the Curators, exhibited a facsimile of the Declaration of Independence in the handwriting

PRINTED JUNE 7, 1898.

PROC. AMER. PHILOS. SOC. XXXVII. 157. F.

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