ELEPHANT AND MASTODON. 



123 



also behind. A depressed disc, bounded by a belt of enamel, shows 

 that the first ridge was partially affected by wear ; and a similar cha- 

 racter shows that the second ridge was slightly touched. A great part 

 of the enamel on the right side of the ridge remains entire. The third 

 and fourth ridges are completely denuded of their shell of enamel, but 

 they were probably qiiite intact. The first and second ridges, which 

 remain, show the longitudinal bisecting line. The valleys are trans- 

 verse, but it is seen that they are interrupted in the middle by an 

 accessory lobule in front and behind each ridge. Their outer termi- 

 nation is bounded by a large depressed mammilla exactly as in ilf. 

 latidens. The enamel is very thick, and shows deep rough lines of 

 longitudinal grooving. The mammillgs of the ridges appear very 

 high, and it is seen that the accessory lobules in the furrows form a 

 projecting loop to the disc of depression exactly as in M. Perimensis. 



Dimensions. 



Inches 



Length of fragment 8-8 



Height from lower surface of ramus to alveolar margin, outside . T'i 



Transverse diameter of ramus at posterior end of tooth . . 6'5 



Length of molar .......... 7' 



Width about middle 3-5 



Height of crown at second ridge 2'6 



Nothing more than the cup of the last molar is shown behind. The 

 lower edge of the ramus is broken off, and shows a canal of about 1-|- inch 

 in diameter, running longitudinally. The nature of this is doubtful. 



This jaw is seen to be of less diameter proportionally than the jaws 

 attributed to M. latidens, more especially the Ava specimen No. 3. There 

 is hardly any matrix to indicate whence the specimen came, and there is 

 nothing of the yellow marly conglomerate generally found on Perim Island 

 fossils. But the characters of the tooth are so close to those of M. Peri- 

 mensis that it is attributed to that species. It is much to be regretted 

 that no record has been kept of the history of this specimen, or wliero 

 it came from. [After having gone over all the collections, the opinion 

 arrived at is that this and the next specimen. No. 103, are more likely 

 to have been from Ava than Perim Island. — 23rd Feb. 1855.] 



No. 103. Mastodon latidens. — Fragment of the horizontal ramus, 

 lower jaw, right side, broken off near the symphysis in front, and im- 

 mediately behind the molar in rear ; broken also at the lower border. 

 It contains an entire molar in situ, being the first of the true molars, 

 and the remains of a worn-out milk molar in front. The crown of the 

 tooth, which is well worn, shows four distinct ridges, the three anterior 

 of which are ground down each into a continuous broad disc, showing, 

 about the middle, the characteristic loop of enamel in front and behind, 

 which indicate the accessory mammillae situated about the middle of 

 the valleys. The last ridge shows two discs, which are distinct, 

 although nearly confluent. The talon is barely touched by wear. 



Inches 

 Length of fragment . . . . . . . . . 6'1 



Height ditto to crown of molar in front ...... 4-7 



Ditto ditto behind ...... 52 



Length of molar . . . . . . . . . .4-1 



Width of ditto at second ridge . . . . . . . I'S 



Ditto ditto fourth ridge 2-2 



Length of fragment in front of molar . . . . . . 1'7 



