DAKOTA AND NEBRASKA. 1G9 



with the frontals. The truncated summits of the latter appear together to have been 

 received into a notch of the parietals, and the intervening suture then advanced along 

 the temporal ridges to the bases of the post-orbital processes when it descended poste- 

 rior to the latter, as in the Musks. 



The upper back portion of the parietals is pierced with a large venous foramen, and 

 one or two small ones. 



The frontals are separated by a comparatively straight suture, as in the Musks. 

 Their fore part terminates as in the latter, nearly on a line with the anterior border 

 of the lachr^'mals. 



The malar is of greater proportionate depth beneath the orbit than in the Deer and 

 Musks, and the process it contributes to the zygoma is much stronger. The suture of 

 conjunction with the maxillary advances to about a line with the middle of the 

 second true molar, when it obliquely ascends to the anterior border of the lachrymal. 

 The facial surface of the latter is proportionately small, and is higher than wide. 



Mandible. — The lower jaw is of much greater proportionate breadth at its back 

 part, as represented in figure 1, plate XIV, than in the Musks and Deer. It is also 

 much more produced backward and to a greater depth than in the latter. The 

 border of the produced portion is bent inwardly, and its convex edge is continuous 

 with the base of the jaw. The latter ascends forward almost without interruption, 

 compared with its condition in the Deer. 



The ascending ramus has a forward inclination, and at the upper part is outwardly 

 impressed with a broad shallow concavity. The condyle has nearly the same form 

 and relative position as in the Deer and Musks. The coronoid process is broken off in 

 the specimens. 



The fore part of the lower jaw o^ Leptomeryx has not yet been found. 



Dentition. — The only teeth o^ Leptomeryxl have had the opportunity of examining 

 are those of the molar series. As previously indicated, these are of the same number 

 and hold the same relative position as in most living ruminants. 



Figure 5 represents the triturating surfaces of the upper, and figure 6 part of the 

 lower molar series oi Leptomeryx, magnified two diameters. 



The true molars are composed in the usual manner among ruminants, the crown 

 consisting of two pairs of crescentoid pyramidal lobes, except the last one below, 

 which in Leptomeryx has an additional pair. They resemble most those of the Deer 

 and Musks, and, as in these when completely occupying the functional position, are 

 inserted into the jaws by distinct fangs. See figure 1, plate XIV. 



The upper true molars of Leptomeryx are almost miniature resemblances of those of 

 the Deer, except that the inner lobes of the crown send no accessory processes into 

 the interspaces separating them from the outer lobes. The external faces of the latter 



22 



