DESCRIPTION OF PLATES. 



49 



Plate XXXVLT. 



Figs. 1 and 1 a. — Mastodon Sivalensis. Portion of lower jaw, right 

 side, with first (a?) and second milk molars. — B.M. 



Length of fragment of jaw, 47 in. Greatest breadth, 2-6 in. Height opposite 

 posterior border of second milk molar, 2-1 in. Length of first molar, '6 in. 

 Greatest breadth, -4 in. "Length of second milk molar, 1*8 in. Greatest width, 

 11 in. 



Figs. 2 and 2 a. — M. Sivalensis. Portion of lower jaw, left side, 

 with symphysis and two outer mentary foramina, and containing first 

 (x) and second milk molars. — B.M. 



Length of symphysis (oblique), 2- in. From first molar to anterior margin of 

 symphysis, 2 - 5 in. Length of anterior or first molar, - 4 in. Greatest width, - 4 in. 

 Length of second molar, 1-9 in. Greatest width, 1*2 in. Length of fragment of 

 jaw, 6-6 in. Greatest breadth, 2'1 in. Height at anterior margin of second molar, 

 23 in. 



Figs. 3 and 8 a. — M. Sivalensis. Portion of lower jaw, right side, 

 with symphysis and third milk, and fragment of fourth, or first true, 

 molars. 1 — B.M. 



Length of fragment, 12 - in. Length of symphysis (ant. post.), 4-4 in. Greatest 

 width of fragment, 3' 8 in. Height at posterior margin of third molar, 4 - 2 in. 

 Length of third molar, 3o in. Greatest width, 2" in. 



Figs. 4 and 4 a. — M. Sivalensis. Fragment of lower jaw, left side, 

 with first ? true molar, imperfect anteriorly. — B.M. 



Breadth of jaw, 57 in. Height, 5'4 in. Length of tooth (imperfect), 8' in. 

 Width, 3-2 in. 



Figs. 5 and 5 a. — M. Sivalensis. Fragment of lower jaw with 

 portion of true molar well worn. Shows well the alternate discs of 

 wear. 



Figs. 6 and 6 a. — M. Sivalensis. Fragment of lower jaw, left side, 

 with penultimate 1 true molar, imperfect behind. 2 — B.M. 



"Width 'of fragment of jaw, 6"1 in. Height, 6 - l in. Length of fragment of 

 tooth, 6- in. Width, 3-2 in. 



Figs. 7 and 7 a. — M. Sivalensis. Fragment of lower jaw, right 

 side, with last true molar, much worn, and imperfect in front. — B.M. 

 Length of molar (imperfect), 8'4 in. Width, 3 - in. 



half way across, but thick. The rest of 

 the tooth is concealed. The two front 

 ridges and talon are slightly touched by 

 wear. Width of tooth at first ridge, 

 2-2 in. Width at second, 2"3 in. Length 

 from middle of first ridge to middle of 

 fifth (excluding talon), 3 - in. The third 

 ridge shows 11 little points. No. 670 

 is the left side of the same jaw with 

 corresponding teeth. The mentary for- 

 amen is very much in advance of the 

 fourth tooth, and placed low.— H.F. 



2 Another specimen of left lower jaw 

 of M. Sivalensis, with what is probably 

 the penultimate true molar, is in the 

 Museum of the Royal College of Sur- 

 geons (Oat. No. 690). It has four trans- 

 verse ridges and a heel of two points, 

 not 5 ridges as stated in catalogue. 

 Length of tooth, 5'9 in. ; width at first 

 ridge, 2-4 in. ; at fourth, 2'5 in.— H.F. 



1 In the Museum of the Royal College 

 of Surgeons (Cat. No. 669) is a beautiful 

 specimen of ramus of right lower jaw 

 of a young M. Sivalensis, with the third 

 milk and first true molar. The anterior 

 tooth is a little broken and worn out in 

 front ; it shows six discs of wear and a 

 large talon ridge. The talon and 4 last 

 ridges are quite distinct, the oth and 

 6th are worn out, and probably an 

 anterior talon was included with front 

 ridge. This would make 6 ridges and 

 a back and front talon, or 8 in all. The 

 tooth has little cement, the ridges are 

 low, and there is great plaiting of the 

 enamel plates in wear. Length of tooth, 

 4-2 in. ; width at last big ridge, 2 4 in. ; 

 width at fourth ridge, 2'0o in. ; width 

 at second ridge, T9 in. The posterior 

 tooth has 5 emerged ridges with a talon 

 in front, extending only from the outside, 



