50 FAUNA ANTIQUA SIVALENSIS. 



Figs. 8 and 8 a. — M. Sivalensis. Fragment of lower jaw, left side, 

 containing a very perfect specimen of the last lower molar. The 

 alternate disposition of the mammilla? of the crown is finely exhibited. 

 Cast in B.M. 



Length of tooth, 8-8 in. Width, 2-9 in. 



Figs. 9 and 9 a. — Mastodon Arvernensis. Fragment shoAving pos- 

 terior half of the last inferior true molar. The mammilla? form two 

 alternate rows as in M. Sivalensis, each ridge being composed of a 

 pair of points. From a cast in Museum of Geological Society. 

 Length of fragment of tooth, 5'6 in. Width, 3.8 in. 



Plate XXXVIII. 



Mastodon Perimensis (Falc. 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 

 in 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 as in 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, 25'5 in. Extreme width of 

 occiput, 20 - in. Height of occiput from condyles, 22-2 in. 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 - 3 in. Estimated 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, 3-4 in. Contraction of 

 muzzle at orbitary foramen, 11*6 in. Vertical diameter of right orbit, 4*8 in. 

 From the auditory foramen to the anterior border of the orbit, 16 - 5. Transverse 



