DESCRIPTION 
OF PLATES. 49 
PLATE XXXVII. 
Figs. 1 and 1 a.—Mastodon Sivalensis. 
Portion of lower jaw, right 
side, with first (wv) and second milk molars.—B.M. 
Length of fragment of jaw, 4°7 in. 
posterior border of second milk molar, 2°1 in. 
Length of second milk molar, 1°8 in. 
Greatest breadth, °4 in. 
isis 
Figs. 2 and 2 a—WM. Sivalensis. 
Greatest breadth, 2°6 in. 
Height opposite 
Length of first molar, “6 in. 
Greatest width, 
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 second molar, 1-9 in. 
Length of anterior or first molar, °4 in. 
Greatest width, 1°2 in. 
Greatest width, -4 in. 
Length of fragment of 
jaw, 6°6 in. Greatest breadth, 2°1 in. Height at anterior margin of second molar, 
WB) tel 
Figs. 3 and 5a.—WM. Sivalensis. 
Portion of lower jaw, right side, 
with symphysis and third milk, and fragment of fourth, or first true, 
molars.!—B.M. 
Length of fragment, 12° in. 
width of fragment, 3°8 in. 
Length of third molar, 3°5 in. 
Length of symphysis (ant. post.), 44 in. Greatest 
Height at posterior margin of third molar, 4°2 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. 
Width, 3-2 in. 
Figs. 5 and 5a.—M. Sivalensis. 
portion of true molar well worn. 
wear. 
Figs. 6 and 6 a.—M. Sivalensis. 
Height, 5-4 in. 
Length of tooth (imperfect), 8° in. 
Fragment of lower jaw with 
Shows well the alternate discs of 
Fragment of lower jaw, left side, 
with penultimate ? true molar, imperfect behind.2—B.M. 
Width of fragment of jaw, 6°1 in. 
tooth, 6°in. Width, 3°2 in. 
Figs. 7 and 7a.—M. Sivalensis. 
Height, 6:1 in. 
Length of fragment of 
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. 
1 Tn 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. Stvalensis, with the third 
milk and first true molar. The anterior 
tooth is a little broken and worn out in 
front; it shows six dises 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 fronttalon, 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, 
4:2in.; width at last big ridge, 2:4 in.; 
width at fourth ridge, 2°05 in.; width 
at second ridge, 1°9in. The posterior 
tooth has 5 emerged ridges with a talon 
in front, extending only from the outside, 
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°2in. Width at second, 2°3in. 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 (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, 5:9 in.; width at first 
ridge, 2°4in.; at fourth, 2°6 in—H.F. 
