102 FAUNA AJS^TIQUA SIVALEXSIS. 



It measures o'15 inches in length by 2"35 inches m -width. 

 As yet there is no evidence of a premolar in the upper jaw. 



Of the true molars, the first or antepenultimate (being the 

 fourth in the order of succession) appears to be represented 

 by fig. 7 of Cuvier's Plate I. of ' Divers Mastodontes.' The 

 anterior part of the first ridge is broken off; the crown consists 

 of three ridges which are far advanced in wear, together with 

 a talon of three tubercles. The dimensions, infei-red from 

 the description given by Cuvier, would be about 4-5 inches 

 of length, by 2 -6 in width. This specimen was brought by 

 Dombey from Peru ; and it is referred by Cuvier to M. 

 angustidens. The penultimate, or second true molar, is repre- 

 sented by the Imbaburra specimen discovered by Humboldt, 

 in the volcanic region of Quito, and seen in fig. 1, tab. ii. of 

 the ' Divers Mastodontes.' Like the two preceding molars, 

 it is of a broad rectangular form, haviiig thi-ee ridges to the 

 crown. The dimensions stated by Cuvier are, 4*7 by 3*35 

 inches. The third or last true molar occurs in sihi, in the 

 cranium belonging to the British Museum, as a solitary 

 tooth on either side, the pentdtimates having been worn out. 

 The crown is composed of four ridges and a large complex 

 heel. The anterior ridges are well worn, and present deeply 

 notched trefoil discs. This tooth, on the left side, presents 

 the following dimensions, viz. length 8-75 inches, width in 

 front 3-75, and behind, 3-25. Another detached specimen in 

 the same collection, and in nearly the same stage of wear, 

 measures only 6-75 inches in length, by 3*5 in front, and 2-75 

 behind. It consists also of four ridges and a heel ; the 

 sinuous hollows between the ridges display a decomposed 

 laj^er of cement of considerable thickness. Other examples 

 of this tooth are shown in De Blainville's Osteographie ; 

 and the same position may be assigned to Dombey's 

 specimen from Peru,' which exhibits four ridges and a 

 compound double heel. Cuvier refers it to his M. angustidens. 

 We have ascertained that the old palate specimen preserved 

 in the British Museum, which is figured and described by 

 Peter Camper,^ referred by him to M. Ohioticus, and by 

 Cuvier to M. angustidens, belongs in reality to this species. 

 Camper, in this instance, as in the case of Michaeli's palate 

 fragment of M. Ohioticus,^ took the posterior extremity of 

 the palate for the muzzle end, and he has in consequence 

 described the back tooth as the front one. This specimen, of 

 which the precise origin is unknown, appears to have been 

 presented to the British Museum by the Earl of Shelbume, 

 with specimens of if. Ohioticus, sent by Croghan, from ISToi-th 



> Oss. Foss. tab. i. fig. 6 of ' Divers | " Nova Acta Petrop. torn. ii. tab. viii. 

 Mastodontes.' I ^ Loc. cit. tab. is. 



