40 AMPHITHERHD.E. 



and opercular pieces,' is no fissure at all ; but, in the two 

 specimen s of Amphitherium Prevostii of the Oxford Museum, 

 and in the larger specimen of Amphitherium at York, which 

 exhibit the inner side of the ramus of the jaw, is a distinct 

 groove with an entire surface, answering to that which 

 exists in the corresponding part of the jaw of the mar- 

 supial Myrmecobius and the Wombat. 



The Myrmecobius is an insectivorous Mammal, and also 

 marsupial, and it does not possess approximated and 

 parallel incisores, but widely separated and diverging ones ; 

 they are, indeed, symmetrical with those of the opposite 

 ramus, as in other Mammalia, but, as no one has yet seen 

 an entire jaw of an AmpJiitlierium or Phascolotherium, 

 it is hard to understand the meaning of the assertion, that 

 their incisores are not symmetrical : they are undoubtedly 

 small; but, if they are almost as large as the supposed 

 canine, such likewise are their porportions in Myrmecobius, 

 and many Insectivora. The lower jaw of AmpMtherium 

 BucJclandi, {Phascolotherium, mini,) is not more arched than 

 in the recent Dasyurus, whose jaw is placed beside the fossil 

 in the British Museum ; and it will be plainly seen that 

 the condyloid, or articular surface, instead of ' passing 

 obliquely into the hard imbedding rock," stands boldly 

 out, and demonstrates a form diametrically opposite to 

 that concave one which characterizes the jaws of reptiles 

 and fishes. Thus much I have thought it necessary to 

 state as to matters of fact, respecting which, however, 

 the specimens speak plainly for themselves. 



Not any of the jaws hitherto discovered present eleven 

 similar multicuspid molares : even in the fragment of one 

 side of the lower jaw figured by M. Prevost, which con- 

 tains ten of the series of twelve molares, which is the true 

 number in the genus Amphitherium, the fractured state 



