DESCRIPTION OF PLATES. 45 
Pirate XXXII. . 
Fie. 1.—Mastodon Sivalensis. Lateral view of same skull as is 
figured in Plate XXXII. Shows temporal fossa and left zygomatic 
arch entire.—B.M. 
Fig. 2.—Palate view, showing palate, one molar on each side, both 
zygomatic arches entire, occipital condyles, &c. Same cranium as fig. 1. 
—B.M. 
Fig. 3.— Occipital view of same cranium, showing occipital condyles 
and foramen, pterygoids, &c.—B.M. 
Fig. 4.—Lateral view of another cranium of M. Sivalensis, with 
lower jaw in situ. The left zygomatic arch is broken away.—B.M. 
PATH eNexeXVE 
Fig. 1.—Mastodon Sivalensis. Portion of skull showing palate with 
two molars on either side, the posterior molar on right side imperfect. 
In this specimen there are two large orbitary foramina and there is 
only a tusk on the right side; the left tusk-sheath is withered. The 
tusk-sheaths are very divergent, with an enormous deep trough 
between, and there is great concavity of the brow, as in H. insignis. 
The teeth diverge anteriorly, as in Mastodon Ohioticus, but in a 
less degree. The molars are excessively like Smith’s specimen of the 
last molar upper jaw, right side, of Mastodon Arvernensis (Plate 
XXXVI. fig. 8). The slope of grinding surface from without inwards 
is very notably seen (see Plate XXX. fig. 3). The anterior molar of 
both sides is worn, but shows four ridges with a heel, the ridges so 
advanced in wear as to exhibit the characteristic alternating discs of 
wear, so remarkable in this species. The last molar is perfect, except 
the heel ridge, on the left side. The front ridge is barely touched by 
wear, while the four back ridges are intact. The drawing does not 
show the characters very perfectly. The front ridge has two confluent 
ridges on the inside and two on the outside, to the inner of which the 
intermediate pillar is attached, joming on with the innermost large 
point of the third ridge. This third ridge shows but one thick point 
on the inner division and two on the outer, with the termediate pillar 
connecting the outer division of the third with the inner division of 
the fourth ridge, and so with the last ridge. This diagonal connection 
of the posterior surface of the outer division with the anterior surface 
of the inner points of the next following ridge cause in wear the 
alternate-like discs of detrition, which characterize the teeth of Mas- 
todon Sivalensis. The same kind of arrangement holds in Smith’s spe- 
cimen of Mastodon Arvernensis. The points in M. Sivalensis are very 
high and obtuse, and the apex of the ridges is high as compared with 
the specimen in Mr. W. Ewer’s collection. (See also antea, p. 117.) 
Length of two molars, right side, 9:2 in. Length of front molar, left side, 4°7 
in.; width, 2°8 in. Length of last left molar minus heel, 6°4 in.; width, 3°0 in. 
Interval between teeth in front, 3°4 in.; interval between teeth aT DAT calit, 
Height of enamel crown, 2°3 in. Height of inner mammilla of second ridge, 1°8 
in. Length of palate from niche to diasteme, 9:0 in. Antero-posterior diameter right 
tusk, 3:0 in.; transverse, 2°7 in. Width of base of muzzle at orbitary forame on, 
14-0 in. Interval between the middle of the orbits, 19°2 in. Antero-posterior 
diameter or height of left orbit, 4°8 in. 
Figs. 2 and 2 a.—M. Sivalensis. Fr agment of upper jaw with molar 
presenting six ridges, with same characters asin fig. 1. The two anterior 
ridges only are touched by wear. The tooth is now cut into sections. 
—B.M. 
D 
