DESCEIPTION OF TLATES. 



469 



Plate XXXVII. 



Figs. 1 and 1 a. — J\fastodon Sivalensis. Portion of lower jaw, right 

 side, with first {x) 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, 

 1-1 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, r2 in. Length of fragment of 

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

 2-3 in. 



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

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

 molars.i — 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, 3'5 in. Greatest width, '!■ 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, 6'7 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 ? true molar, imperfect behind.^ — B.M. 



Width of fragment of jaw, 6"1 in. Height, 6'1 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 Iront. — B.M. 

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



' 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 5th 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, 2-05 in. ; width 

 at second ridge, 1-9 in. The posterior 

 tooth has .5 emerged ridges with a talon 

 in frrr.t, extending only from the outside. 



half way across, but thick. The rest of 

 the tooth is concealed. The two front 

 ridges and talon are slightly touched liy 

 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. 



^ Another specimen of left lower jaw 

 of M. Sivalensis, with what is probably 

 the peniiltimate true molar, is in the 

 Museum of the Royal College of Sur- 

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

 verse ridges and a heel of two points, 

 not 5 ridges as stated in catalogue. 

 Length of tooth, 6'9 in. ; width at first 

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



