38 PACHYDERMATA. 



prising the sixth and seventh ridges. The cement exhibits 

 an appearance of lamination, of which from nine to eleven 

 layers may be counted, and is developed in as great a quantity 

 as the intervals between the ridges could admit of. The four anterior 

 ridges have been well used, so that the two first are worn down 

 to a common disc, from which the enamel has disappeared ; and the 

 cement of the four anterior hollows, being the softest of the tooth 

 substances, has been completely, or partially, worn away by the 

 same process of detrition. The dark granulated shade below the 

 portion of the ivory nucleus which sustains the five posterior ridges, 

 indicates, in the figure, the hollow of their common posterior fang, 

 which is occupied in the "fossil by a core of sandstone ; the same 

 matrix also fills the cells of the maxillary bone. The anterior 

 simple fang is shown in the section, of much smaller size. This 

 tooth measures 10.3 inches in length. 



Fig. 6 b, represents a similar section of the anterior portion of 

 an adult tooth of the lower jaw of the same species. In this 

 instance the two front ridges only, have been touched by wear. 

 Instead of being convex, the common curve of the crown is slightly 

 concave. The ivory, enamel, and cement present the same cha- 

 racters as in the upper molar, except that the cement in the 

 interspaces is less considerable in quantity, although sufficiently 

 abundant to indicate that it was functionally serviceable in the 

 grinding operation of the tooth. The posterior part of the basal 

 portion of the pulp nucleus had not yet completed the stage of 

 calcification, its place being occupied in the fossil by a nest of 

 calcareous crystals, bounded in the figure by the undulated line. 

 The figure shows also a portion comprising the two last ridges of 

 the preceding molar, with their common fang implanted in the 

 lower jaw. 



The next serial modification in the disposition of the three 

 dental substances, and in the consequent form of the teeth, is 

 exhibited in fig. 5 a of the same plate, which represents a section 

 of the penultimate upper molar of another Indian fossil species 

 which we have named E. planifrons. This tooth shows nine 

 ridges, the three anterior of which alone have been in use, the 



