INTRODUCTION. 73 



nianent separation of the squamous, petrous, and 

 tympanic elements. "' I Lave observed/' says Pro- 

 fessor Owen_, "this reptile like condition of the bone in 

 the mature skulls of an Ursine Dasyure, a Virginian 

 Opossum, a Perameles, in different species of Potoroo, 

 (or Kangaroo-rats,) aiid Kangaroo, in the Wombat, 

 and in the Koala."* The palatine portion of the 

 skull is nearly always very imperfect, presenting 

 large openings, and here again we find much differ- 

 ence between the Carnivorous Marsupials and the true 

 Carnivora, these latter wanting the large posterior 

 openings to the palate which characterize the former. 

 Lastly, I would call attention to a remarkable pecu- 

 liarity in the lower jaw of the Marsupiata : in all 

 the species of this group of animals, (with the excep- 

 tion of the Echidna and Orniihorhynchus) " the angle 

 of the lower jaw, is as if it were bent inwards, in the 

 form of a process encroaching in various shapes and 

 various degrees of development, in the different Mar- 

 supial genera, upon the interspace of the rami of the 

 lower jaw. In looking down upon the lower margin 

 of the jaw, we see therefore, in place of the margin 

 of a vertical plate of bone, a more or less flattened 

 surface, extending between the external ridge and 

 the internal process, or inflected angle."t 



The reader who is anxious to enter deeply into 

 the study of this interesting group of Quadrupeds is 



* On the Osteology of the Marsupialia. Proceedings of the 

 Zoological Society, for October 1838. 



i" Professor Owen. Osteology of the Marsupialia, before 

 quoted. 



