38 AMPHITHERIID^E. 



These jaws have the coarse fibrous structure, and dark 

 glistening surface from the abundant proportion of animal 

 matter common in fossil cold-blooded Vertebrata, and their 

 composite structure is obvious, from the distinct deep 

 fissure extending along their base between the dental and 

 opercular pieces ; the articulated pieces of these compound 

 jaws more or less resemble the coronoid, condyloid, and 

 angular, processes of carnivorous Mammalia, as they do 

 also in most osseous fishes, but most distinctly in Reptiles, 

 where the detached elements of the jaw are more numerous. 

 The teeth are often black, glistening and bituminous from 

 their abundance of animal matter and carbon, as in most 

 fossil fishes ; their crowns are compressed, free, multicuspid, 

 and their cervix much contracted and long, as in the 

 Amboyna lizard, the iguana, iguanodon, many fishes, &c., 

 and their surface is minutely furrowed with close vertical 

 grooves near their cervix, as in most Saurian reptiles and 

 Sauroid fishes. The fangs are deeply implanted in the jaw, 

 as in all the Acanihuri, &c., and they are bifid, as in 

 many Squali, and in the closely allied Basilosaurus. At 

 least eleven similar multicuspid molars are seen in a frag- 

 ment of one side of the lower jaw, as commonly observed 

 in fishes and reptiles, but never in mammiferous quad- 

 rupeds. 



" I have examined four of these jaws in England which 

 have been referred to didelpTiis ; and the jaw at Paris, 

 from the same locality as the others, is acknowledged 

 by all to belong to a reptile, as demonstrated by Blain- 

 ville. The supposed incisores, instead of being small, 

 symmetrical, approximated, and parallel, as in insectivorous 

 and carnivorous mammalia, are long, conical, irregular, 

 widely separated from each other at their base, almost 

 as long and large as the supposed canine, and diverging, 



