SYSTEM OF NATURE. 
37 
gest whether that remarkable extinct animal, the Ptero- 
dactylus, was not a marsupial rather than a reptile. I 
am led to this supposition by certain peculiarities in the 
bones of Pterodactylus, which, had they been noticed by 
competent zoologists, I would have detailed, but I fear to 
trust to my own slender knowledge of these matters, and 
therefore dismiss the subject, hoping my suggestion may 
catch the eye of some zoologist competent to decide on 
its merits. 
The pterodactyles, although at present treated as a ge¬ 
nus, constitute a much higher division than those usually 
denominated by that name. Whether these remains even¬ 
tually prove to have belonged’to reptiles or marsupials, the 
animals must have constituted a group as extensive and as 
diversified as the Ferse, Cheiroptera or Glires at the pre¬ 
sent day: the three species, Pter. longirostris, Pter. cras- 
sirostris, and Pter. brevirostris, are remarkably distinct 
forms, and totally different in their dentition. 
3rdly. Their antiquity. One other subject connected 
with their distinctness and inferiority, as compared with the 
placentals, has occurred to me. It is generally admitted by 
geologists, that the more ancient the formation they examine 
the lower in the scale have they found the synchronous 
race of animals. Now I think it is established beyond a 
question, that in more than one instance the remains of 
marsupials, birds and reptiles occur simultaneously, with¬ 
out the slightest trace of the synchronous existence of any 
placental animal. I observe Dr. Mantell has been struck 
with this, as, after giving a comparative list of the organic 
remains of the grit of Tilgate Forest and the Stonesfield 
slate, in the latter of which occur marsupials and in the 
former birds, lie observes, “ the remains of Cetacea do not 
