56 AMPHITHERIID.E. 



me soon after it came into his possession, and on being 

 made acquainted with my wish, he kindly permitted me to 

 take the requisite means to determine the shape of the 

 angular process. The external surface, the only part ex- 

 posed, was quite entire ; and with a fine graving-tool, I 

 cleared away sufficient of the matrix to show the extent to 

 which it was imbedded. Although the inferior margin of 

 the process is inflected so as to render the outer surface con- 

 vex, the degree of inflection is less than in any of the 

 known Marsupialia, and does not exceed that of the Mole 

 or Hedgehog. This slightly inflected margin is broken 

 away, in both the half-jaws that have their inner surface 

 exposed, and if that indication of an inflected angle has 

 been insisted upon too strongly as a marsupial character, 

 we may be warned thereby to avoid the opposite extreme 

 of concluding too absolutely, that a Mammal, with such 

 peculiar dental characters as those of the AmpMtJierium, may 

 not have combined the more essential points of the Marsu- 

 pial organization, with the lowest development of that 

 peculiar character of the existing species, which is afforded 

 by the angle of the jaw.* 



The main fact in the present inquiry, the antiquity of 

 the Mammalian type of organization, is, if possible, more 

 unequivocably established by the present than by the pre- 

 ceding fossils. The whole outer surface of the ramus of 

 the jaw is beautifully entire : not a trace of the alleged dis- 

 tinct, deep fissures which, in Lizards and other cold-blooded 

 Ovipara, separate the coronoid or complementary and other 

 elements of the jaw can here be discerned. The broad and 

 simple coronoid process shows the wide concavity and the 



* The ossa marsupialia even, may be absent, without the loss of the essential 

 organic Characters of the Marsupial Order, as I have lately ascertained by dissec- 

 tion of the great carnivorous Opossum (Thylacintts Harrisif) of Van Dieman's 

 Land. 



