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Show 121 M. Diameter of canine at base 025 Length of penultimate inferior molar 030 Width of penultimate inferior molar 021 Individuals of larger size than the above are more common. Measurements of one of these are: M, Length of last superior molar 032 Width of last superior molar 043 Diameter of crown of canine, ( another species) 030 This is the especially characteristic large mammal of this fauna, and must have* existed in herds. BATHMODON MOLESTUS, sp. nov. Established on remains of one species and probably respresented by those of others in possession of the expedition. The teeth differ in several important respects from those of B. radians and B. simus. Thus the canine is quite compressed in the coronal portion, and is narrow triaugular iu section, the narrow base of the triaugle being concave ; that is, the section of a strong groove, which is bounded by a sharp edge on each side. The edge proper of the crowu is also duplicated by a ridge of the enamel, which joins it at an acute angle. The last upper molar is characteristic in it* wide crown, the posterior usually transverse crest being curved so as to represent the segment of a circle, the convexity posterior. The ramus of the lower jaw is very slender. The posterior inferior molar is large, and has subequal transverse crests. The posterior ciugulnm, which descends from the external angle, is moderately developed on both of the crests. In a young specimen of this or an allied species of Bathmodon, the deciduous tooth which is replaced by the last premolar has two external crescents; an interesting point of resemblance to the Perissodactyle ungulates. Measurements. M. Width of anterior crest of last inferior molar - « .023 Width of anterior crest of superior molar 039 Length of superior molar 029 Antero- posterior diameter of crown of canine 022 Transverse diameter of crown of canine 013 Depth of mandible at last lower molar , .050 BATHMODON LOMAS, sp. nov. The very numerous remains of the genus Bathmodon obtained are referrible to several species, as- indicated especially by the teeth. The present form is characterized among other points by the form of the last inferior molar. The anterior crest is much more elevated than the posterior, with its inner apex almost a cone, with anterior, thick, revolute border. The usual oblique cingulum descends from the outer apex forward. The longitudinal ridge connecting the crests is low but distinct, while the posterior cingnlar ridge is remarkably large. This, which constitutes one of the specific marks, is extended horizontally so as to form a broad ledge, whose border is a segment of a circle. Enamel roughened with five ridges on all the external surfaces. Tooth well worn by prolonged use. Measurements. M. Length of crown 041 Width of crown anteriorly 027 Width of posterior crest .022 Elevation of posterior crest 011 Elevation of anterior crest 024 BATHMODON ELEPHANTOPUS, sp. nov. The most abundant species of the New Mexican Eocene formation, and of the largest 6ize, exceeding in this respect both the Bi simus and B. molestus. I describe at present the last molars of both superior and inferior series. The former is a transverse oval, slightly swollen on the posterior border external to the middle point. The two crests are parallel, the anterior as usual curving round to the inner extremity of the shorter posterior, and leaving a wide interval between them. The posterior is not divided, but is elevated at the extremities. Anterior ciugulnm strong, posterior obsolete, excepting on the external border, where it sends a low ridge to the elevated extremity of the anterior crest. Exteroariterior to this ridge is a shallow fossa. Enamel very slightly rugose. The posterior lower molar exhibits a great disparity of elevation of the crests, the anterior being high, and terminating on the inner side in an elevated cone. The con- |
