48 The American Naturalist. [January, 
characterized by a development of the horn-cores so far unique in the 
genus. I characterize it under the name of 
MENODUS PELTOCERAS sp. nov.—Represented by the nasal region 
and the horn-cores; the apex of one of the latter being broken away. 
The peculiarity of the species consists in the immense transverse extent 
of the horn-cores, and their complete fusion into an osseous wall which 
extends across the muzzle, forming a huge plate or shield.. The supe- 
rior border of this shield is moderately concave, a protuberant angle 
on each side representing the apex of each horn-core. The nasal 
bones form a flattened protuberance much wider than long, which 
overhangs the nares. Their superior wall slopes directly upwards from 
the obtuse apex to the crest of the horn-core-plate. The expanse of 
the base of each horn-core outside of the nares is as wide as the nasal 
meatus, is flattened from before backwards, and has a narrow external 
margin. The horn-core-plate is vertical behind at the slightly angu- 
lated middle line, and is moderately concave on each side, the apex 
being slightly recurved. Measurements: Elevation of horn-core-plate 
at middle line behind, 180 mm. ; do. at lateral apex, 190 mm. ; total 
width of do. at middle, 300 mm. Projection of nasal bones beyond 
lateral base of horn-core-plate, 20 mm. ; width of nasal meatus at base 
of nasal bones, 65 mm. ; width of base of horn-core-plate outside of 
nasal meatus, 901 mm Anteroposterior diameter of base of horn-core 
above side of and parallel to nasal meatus, 85 mm. ‘This species is 
nearest the M. platyceras S. & O., which has transverse comp 
horn-cores. They are, however, distinct from each other, and not 
nearly so expanded transversely as in the present form. The M. pelto- 
ceras, in fact, carried a transverse shield on the end of its nose, which 
must have given it an extraordinary appearance. 
CNOPUS SIMPLICIDENS sp. nov.—Represented by the last two — 
superior molars of the left side, with a probable humerus and femur. — 
The molar teeth are one-third larger in linear dimensions than those of 
the C. occidentalis Leidy, and lack the external basal cingulum which 
1s present in the corresponding teeth of that species. Internal cingu- — 
lum wanting, but the anterior and posterior cingula present. The — 
posterior limb of the metacone is represented in the posterior molar by 
a tubercle at the base of the crown, which rises into a a low ridge — 
which soon disappears. It bounds a fossa with the posterior cingulum 
just behind it. Transverse crests simple, with a convexity representing - 
the anti-crochet. Paracone distinct, separated by an open groove from 
the anterior angular cone. Both limbs of the metacone of the penulti- a 
mate molar are well developed. Measurements: Transverse diameter - 
