50 FAUNA ANTIQUA SIVALENSIS. 
Figs. 8 and 8a.—WM. Sivalensis. Fragment of lower jaw, left side, 
containing a very perfect specimen of the last lower molar. The 
alternate disposition of the mammille of the crown is finely exhibited. 
Cast in B.M. 
Length of tooth, 8°8in. Width, 2-9 in. 
Figs. 9 and 9 a.—Mastodon Arvernensis. Fragment showing pos- 
terior half of the last inferior true molar. The mammille form two 
alternate rows as in MW. Sivalensis, each ridge being composed of a 
pair of points. From a cast in Museum of Geological Society. 
Length of fragment of tooth, 5-6in. Width, 3.8 in. 
Puate XXXVIII. 
Mastodon Perimensis (Fale. and Caut.), from Perim Island. 
Front view of skull. Other views of same skull are given in Plate 
XXXIX. figs. 1, 2, and 3. 
This cranium is in many respects singularly perfect, although it has 
_ suffered from a crushing force, which has forced in the temples, so as 
to have contracted to a few inches the inter-temporal portion of the 
forehead. The ascending ramus of the lower jaw on either side is 
én situ with the coronoid process and condyle, and, what is more 
remarkable, the greater part of the hyoid bone lies upon the 
sphenoid. The atlas also was found attached to the condyles. The 
teeth are completely hammered down to the margin of the alveoli. 
The most remarkable character of all about this head is the low height 
of the pterygoid processes of the sphenoid, which are very little higher 
than the condyles, and the comparatively little elevation of the condyles 
above the palate. The interval between the plane of the lower surface 
of the condyles and that of the palate is only 5 inches, the height of the 
occiput being 22 inches. This is very much asin the North American 
Mastodon, and even more so, so that the plane of the grinder does not 
differ much from that of the condyles, thus showing a tendency in the 
direction of Dinotherium and the Trilophodon Mastodon Ohioticus. 
The pterygoids rise with a sharp posterior border, and do not spread 
out into a flap over the posterior border of the maxillary. They are 
not rugous as M. Ohioticus, nor are they so far (proportionally) ex- 
tended behind. There are two large palatine foramina near the end 
of the molar. The molars (allowing perhaps for some distortion from 
pressure) run parallel, and do not at any rate diverge in the remark- 
able way exhibited by M. Ohioticus; perhaps they are less divergent 
even than in M. Sivalensis. The palate looks long. On either side 
are two molars, the penultimate and last true. The tusks exhibit an 
oval outline on section. Both zygomatic arches are entire. Presented 
by Captain Fulljames to B.M. 
Extreme length from occiput to broken incisives, 27’in. From posterior surface 
of occipital condyles to commencement of diasteme, 25°5in. Extreme width of 
occiput, 20°in. Height of occiput from condyles, 22°2in. From occiput to 
broken tips of nasals, 13:in. From tips of incisives (anterior end of nasal open- 
ing) to commencement of diasteme, 14°5 in. Width of nasal opening (approximate) 
9-8in.; antero-post. diameter of nasal opening, 4°3in. Hstimated width of brow 
at post. orbitaries, 19°in. Width of brow at middle of orbits, 15°in. Width of 
inter-incisive fossa, 2°2in. Depth of inter-incisive fossa, 3-4in. Contraction of 
muzzle at orbitary foramen, 11°6in. Vertical diameter of right orbit, 4°8 in. 
From the auditory foramen to the anterior border of the orbit, 16°5. Transverse 
