Osteology of Loxomma Allmanni. 53 



looks like a fracture, exposes the inner surface of the teeth as 

 far as to near their roots, and the depressions between the teeth 

 appear as if in section. 



The exposed surfaces of the teeth are closely invested, 

 however, by a thin layer of osseous tissue continuous with 

 that covering the surfaces of the depressions, and the inner 

 alveolar border has not in reality been broken off. The teeth 

 of this half-mandible are differently arranged as to size and 

 position from those of the right half. 



The row of teeth begins in front, as in the other half- 

 mandible, with a small one ; next to this comes the largest 

 tusk, behind and internal to which is the largest depression, of 

 a nearly circular outline ; next come two small teeth with a 

 very narrow depressed interval between them ; and below the 

 former of these it is that the alveolar border begins slightly to 

 be deficient ; then we have the second depression, followed by 

 two teeth separated by a depression broader than the last : 

 immediately behind the latter of these two teeth is a large and, 

 as it were, double and deep depression 1\ inch broad; this is 

 succeeded by three tusks separated from each other by two 

 large depressions ; after the last of these three tusks is a broad 

 depression followed by a rather small tooth ; lastly, behind 

 this are two other teeth still smaller, with very short intervals 

 between them ; and the fractured end of the bone occurs directly 

 after the latter of these teeth. 



The teeth (Plate VII. figs. 2, 3, 4, 5, 6). With the excep- 

 tion of four on the right side of the cranium, three of which 

 belong to the maxillary and one to the premaxillary, nearly 

 half of the teeth of the right ramus, and one of the left half 

 are broken off, as before stated. Their fracture is transverse, 

 giving a circular outline, within which can be roughly seen 

 their beautiful labyrinthodont structure. Several other spe- 

 cimens, however, of Loxomma have been found, of which the 

 teeth are entire. 



The size of the teeth varies both in the upper and the lower 

 jaw, those of the vomerine plates and of the palate-plates of 

 the maxillaries being much larger than those of the alveolar 

 borders of the maxillaries and premaxillaries ; the second 

 tooth of the left half of the lower jaw is much larger than any 

 of the others of that part; the ninth, the seventh, and the 

 eighth come next in order of size, and occupy a middle posi- 

 tion in the ramus. In the right half, the second, eighth, and 

 twelfth are the largest, differing but little in size from each 

 other, and the sixth is next ; the twelfth is in advance of the 

 middle of the jaw. The teeth of the mandible are more deeply 

 socketed than those of the maxilla ; all are expanded at the 



