74 FAUNA ANTIQUA SIVALEXSIS. 



ridge. Tliis tooth belongs to one of the forms which ha,ve 

 been iuchided under the name of Mast. Elephanto'ides, by Mr. 

 Clift, and which Professor Owen names ' Transitional Mas- 

 todons.' It is import.ant to observe the characters presented 

 by the cement in this case, as its supposed absence or presence 

 in the molar teeth was the princij)al character upon which 

 Cuvier rested his generic distinction between Mastodon and 

 Elephant. Professor Owen, in his ' OdontogTaphy,' states, in 

 regard to the teeth of this species, that ' the intersj^aces are not 

 filled with cement, as in the true elephant : only a thin layer 

 of that substance is continued vipon the unworn enamel, as 

 in the true mastodons.' ' But this statement must be received 

 with some modification. [Fig. 7, PI. YI., P.A.S., represents a 

 portion of the same section drawn to the natural size, and 

 comprising 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 

 qua,ntity as the intervals between the ridges could admit of.] 

 The foiu- 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 (PL lY. fig. 1), the hollow of their common poste- 

 rior fang, which is occupied in the fossil by a core of sand- 

 stone ; 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 h, P.A.S., represents a similar section of the anterior 

 portion of an adult tooth of the lower jaw of the same species. 

 In this ulstance 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 characters 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 then- common fang implanted in 

 the lower jaw. 



' Odontography, p. 62-t. 



