118 FAUNA ANTIQUA SIVALENSIS. 



Inches 

 Extreme length of fragment . . . . . . . .7" 



Height from molar surface in front to upper edge of fracture . 43 



Length of crowii of third milk molar ...... 3'2 



Width of ditto in front 1-8 



Ditto ditto behind 2-1 



Ditto of back molar at third ridge ...... 25 



Length of alveolar space of second milk molar (fallen out) . . 1 '2 



Width of ditto in front 1-3 



Ditto ditto behind 1-5 



This is a very important specimen from sliowing so much of the early 

 dentition. It is evidently a yoimg M. Sivalensis, but there is nothing 

 to indicate the locality whence it came. 



No. 2. Mastodon Sivalensis. — Fine specimen showing the tipper 

 maxilla, both sides, with the last milk molar and first true molar in 

 situ, closely resembling specimen No. 1. The specimen is broken 

 lengthways along the palate into two fragments, and it is a good deal 

 covered with sandstone matrix. The anterior molar on the left side 

 has the greater part of the cro^vn hammered off by attrition. On the 

 right side, what remains of it shows discs of considerable wear. The 

 back molar, on either side, is in a state of germ. It resembles No. 1 

 so closely, that further details are unnecessary. 



B. From Ava. 



No. 1. Mastodon latidens. — Fine specimen of the upper jaw, both 

 sides containing one entire molar in each, and the anterior ridge behind 

 of another molar germ. The specimen is broken off horizontally about 

 four inches above the base of the cro\vn of the molars, showing the floor 

 of the nasal fossa. The palate is perfect from the posterior border to the 

 commencement of the diasteme, where it is abruptly broken off. The 

 teeth are in the most perfect state of preservation ; the enamel is thick, 

 riigose at the sides, and presents on the crown a clouded pearly 

 appearance ; the anterior of the molars consists of four ridges and a 

 talon or heel ridge; the three anterior ridges are more or less worn, 

 the fom-th ridge only slightly touched in the middle ; each tooth 

 exhibits longitudinally a line bisecting it into an outer and an inner 

 half; the ridges are transverse, the furrow intervening being unbroken, 

 with a small mammillary process boimding the interior termination of 

 the furrow and interposed between the ridges. These mammiUary pro- 

 cesses are chiefly seen in the first and third furrows ; they are absent from 

 the second. Each ridge near the middle throws oiit one or two accessory 

 adpressed mammilla behind, which encroach on the fruTOWs without 

 distm-bing their continuity, causing loops of wear when the ridges are 

 groimd down ; there are about six mammillae to each ridge, the inner- 

 most of which is the largest. The talon on both sides forms a rather 

 complicated ridge, more largely developed than in most other species 

 of mastodon. The first and second ridge of the left molar are worn 

 down, so as to show continuous depressed discs of ivory surrounded 

 ' with a border of enamel. The third ridge shows three small discs, the 

 outermost mammilla being hardly touched ; the fourth ridge and the 

 talon are hardly touched ; on the right side, the anterior ridge forms 

 also a continuous depressed disc, the second ridge is distinctly bijjartite 

 into discs of an irregular pattern, with a loop in each behind, caused 



