AMPHITHERIUM. 39 



as the front teeth of anarrhichas and many other fishes. 

 There is a hinge-like, dentated appearance, consisting of 

 three similar and equally distant grooves, as between the 

 rami of the lower jaw of most osseous fishes, distinctly 

 perceptible in Amphiiheriwm Bucklandi, at the broken 

 surface of the symphysis, and the lower jaw is arched, 

 as in most fishes and Saurian reptiles. The coronoid, 

 or complementary piece, is deeply concave interiorly, and 

 its anterior suture is seen extending to the third posterior 

 molar tooth, as in the Iguana. The condyloid, or arti- 

 cular surface, passes obliquely into the imbedding hard 

 rock, and may be concave, as in reptiles and fishes, but 

 is not exposed. This animal has received its name from 

 the mixed and ambiguous character of its relics, and the 

 foot-marks of Chirotherium, left on the new red sandstone, 

 have been referred to a similar didelphis existing at that 

 early period. The great jaws, teeth, and vertebrae of Basi- 

 losaurus, approaching closely in its characters to Amphi- 

 therium, were found in the oolite of the New World." 



The high importance of the question touching the anti- 

 quity of Mammalian organization calls for a due notice 

 of the foregoing statements relative to the most inte- 

 resting fossils which have yet been- discovered, and the 

 more imperatively in this place, since they are peculiar 

 to Great Britain, and, despite the numerous objections, 

 are here admitted into the series of its fossil Mammalia. 



First, then, as to the alleged facts respecting these fossils of 

 the Stonesfield Oolite, repeated scrutiny enables me to state, 

 that, instead of presenting 'the coarse fibrous structure 1 com- 

 mon in fossil cold-blooded Vertebrata, they have the pecu- 

 liarly fine, compact structure which the jaws of insectivorous 

 and marsupial Mammalia manifest. The alleged ' distinct, 

 deep fissure, extending along their base, between the dental 



