100 FAUNA ANTIQUA SIVALENSIS, 



with, the young- teeth of M. longirostris than with those of M. 

 angustidens. The dimensions of the second milk molar are — 

 length, 2-6 inches, width in front 1-3, behind 1-5 ; and of the 

 third — length, 3-5 inches, width in front 1-7. M. Andium, 

 therefore, differs from M. Ohioticus, and diverges more from 

 Dinotherium and the ordinary Pachydermata than does that 

 species, by having a more complex crown in the second milk 

 molar. It supports the presumption that the same tooth in 

 M. angustidens was also three-ridged. Neither in this speci- 

 men, nor in the more advanced one next to be described, is 

 there any indication of an inferior premolar. 



The first and second true molars (being the fourth and fifth 

 in the order of succession) are equally well seen in a fine and 

 hitherto undescribed specimen, also of the left half of the 

 lower jaw of an adolescent M. Andium from ChUi, belonging 

 to the Canterbury Museum (Plate VIII. fig. 2, copied from 

 Plate XL. fig. 15, P.A.S.).' This fragment contains both of 

 these teeth in situ, with the pit of the fang of the third milk 

 molar, which had dropped out, and the formed alveolus of the 

 last true molar. The anterior tooth is somewhat worn, and 

 consists of three ridges of complex composition which have 

 rubbed down under the process of mastication into deeply 

 notched trefoil-shaped, or occasionally quadrilobed, discs, to- 

 gether with a talon of two points. The posterior (being the 

 penultimate) is intact, and also has its crown composed of 

 three principal ridges, with a hind talon. Both of these teeth 

 are more rectangular in form and relatively broader in front 

 than the same grinders of M. angustidens. In this respect, 

 their proportions resemble those of 31. Ohioticus. The ante- 

 rior tooth or antepenultimate true molar measures in length 

 4 inches, vndth in front 2-45, and behind 2-55. The penulti- 

 mate is partly concealed in the alveolus ; the estimated length 

 is about 5 inches, and the width in front 2*75 inches. 



The perfect lower jaw belonging to the nearly entire adult 

 cranium of this species, from Buenos Ayres, now displayed in 

 the British Museum (PI. YIII. fig. 3, or PI. XXXV. fig. 3, 

 P.A.S.), completes the evidence regarding the inferior teeth 

 by presenting the two last teeth in situ. The anterior of these 

 confirms what is shown by the Canterbury specimen respecting 

 the penultimate. It is in an advanced stage of wear, but 

 exhibits distinctly the discs of three ridges. The crown is 

 nearly rectangular in form, the dimensions being- 5*1 inches 



1 My best acknowledgments are due | montlis. The excellent public museum 

 to Alderman Masters, of Canterbury, for | in Cantorliury, liiglily creditable to a 



enabling me to examine this very valu- 

 able specimen with leisure in London, Ijy 

 putting it at my disposal during several 



provincial city, owes its origin and pre- 

 sent condition chiefly to the well-directed 

 exertions of Mr. Masters. — [H. F.] 



