40 PACHYDERMATA. 



narrow wedge-shaped plates, the height of which is many times 

 greater than the width of their base. The interspaces of the 

 plates are proportionally deep, and filled up with a copious mass 

 of cement, which completely envelopes the tooth. The quantity 

 of this substance is measured by the proportion which it bears to 

 the other dental materials, and it is seen to be thicker than the 

 ivory plates. The layer of enamel is reflected over the ridges 

 and down upon the hollows as in E. insignis, but it is much 

 thinner, and the attenuation is proportioned to the elongation of 

 the plates. The common basal mass of ivory is greatly reduced 

 in quantity, if compared either with the sections of E. insignis, 

 fig. 6 a, or of E. planifrons, fig. 5 a, there being little more of 

 this substance than is sufficient to establish a common connection 

 between the bases of the segments, and a foundation for the 

 offset of the fangs, which are numerous. The vertical height 

 of the tooth is considerably greater than that of either of the 

 two other described species. This tooth measures 8.7 inches in 

 length. 



Fig. 4 b, represents a penultimate molar of the lower jaw 

 of the same species in vertical section. Like that of the upper 

 jaw, it is composed of nine cuneiform plates. This tooth had 

 been a long time in use, all the plates except the last being 

 affected by wear. The anterior part of the crown has been 

 ground down to nearly one-third of its original height, so that the 

 enamel divisions between the two anterior ivory plates have 

 disappeared, and the latter are confluent into a common mass. 

 It is not, therefore, in the condition best adapted to show the cha- 

 racters presented by a good section ; but it indicates sufficiently 

 the correspondence of the lower with the upper molars, in the 

 disposition, form, and relative proportion of the ivory, enamel, 

 and cement substances. It bears a very close resemblance to the 

 section of the lower molar of E. planifrons, fig. 5 b, keeping 

 in mind, that the latter is taken from an older and larger tooth. 

 They exhibit the same kind of wedge-shaped ivory plates, a 

 similar amount of cement in the interspaces, and an analogous 

 thickness of enamel. The resemblance between the lower, in 



