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this and other characters of the species are more fully and plainly illustrated by the 

 specimens next to be described, of which I commence with the portion of a left maxil- 

 lary, forming the subject of figures 2, 3, 4 of Plate XCIV. 



This portion of jaw retains the five permanent molars (p 3 to m 3 ), but with some 

 mutilation as well as wear of their crowns. The fore pier of the zygoma (ib. fig. 2, 21") 

 springs out above the interval between the second (d 4) and third (m 1) molars ; and as 

 the last (m 3) is in place and shows wear, it may be concluded that this anterior portion 

 ot that pier is characteristic of Procoptodon. 



On the palatal surface of the bone (ib. figs. 3 & 4) the evidence of the same large 

 vacuity as is indicated in the smaller species (Procoptodon Pusio, Plate XC. fig. 6) 

 is unmistakable. The anterior ridge begins to curve to join its fellow opposite the 

 second molar (d 4), the junction taking place at the mid interval between the right and 

 left premolars (p 3) ; the posterior ridge similarly bridges the palate between the alveoli, 

 right and left, of m 2 & m 3, fig. 4, Plate XCIV. 



On the working-surface of the crown of p 3 the transverse ridges of enamel along the 

 tract occupying the fore and inner part of that surface appear. This tooth is broadest 

 behind ; it is supported by three stout fangs ; the foremost diverges from the hind pair 

 as it ascends into the substance of the jaw, where two thirds of an inch of it is exposed ; 

 it is thick, and the cemental coat is longitudinally and irregularly striate. 



At the back part of in 1 two of the deep vertical notches (ib. fig. 9, h) and the intervening 

 strong ridge of enamel (ib. g) are conspicuous. The fore link (s) and the accessory link 

 to its inner side, also the mid link and the accessory ridges on the surfaces of the lobes 

 internal to it, are shown. The prebasal ridge (f), with the fore link (s) of the last molar 

 (m 3, fig. 4), has been broken off and slightly displaced from the rest of that tooth, in 

 which the indents and ridges on the hind surface are well displayed. At every part of 

 the worn and fractured surface of this molar series the stalactitic-like complexity of the 

 thick and hard enamel is exemplified. The figures being of the natural size preclude 

 the need of giving dimensions of the several teeth. 



In the smaller portion of maxilla and molar series (Plate XCIV. figs. 5, 6, 7) the 

 coronal modifications of m 1 and in 2 are instructively displayed. Viewing the working- 

 surface from above, the postbasal ridge seems to be represented by a short bar of enamel 

 (figs. 7 & 9, g) supporting the bases of the narrow but strongly developed pyramidal 

 ridges (ib. It), sending their apices to the working-surface of the hind lobe ; but the 

 basal bar does not project like a true basal ridge from the hinder convex surface of the 

 crown (fig. 9). 



The correspondence of the complex pattern of the crown of the lower with the upper 

 molars, combined with the usual modifications of greater length of the prebasal ridge, is 

 patent in the subject of figs. 1 & 2, Plate XCV. In this fossil the last molar (m 3) 

 had but recently risen into place, and the antecedent one (m 2) showed slight traces of 

 abrasion. In d 4 the front lobe (a) is narrower than the hind one (b) ; these proportions 

 are reversed, but in a minor degree, in the last molar (m 3). The fore (s) and mid (r) 



48* 



