OHIRONECTES. 
531 
as large again, and both are of a triangular form, with 
apparently two roots. The three real molars are of the 
normal form of these teeth among the Opossums. The 
first of the upper jaw is longer than broad, and has four 
sharp, elevated tubercles, with a low heel projecting back¬ 
wards ; the second resembles it iu general form, but is larger 
and broader; the third is small, and resembles the tuberculous 
molars of the true Carnivora. In the lower jaw the three 
real molars do not materially differ in point of size : they are 
narrower than those of the upper, have their tubercles arranged 
in a single longitudinal series, a single large one in the centre, 
and a smaller one on each side.” This last phrase p>oints 
out a difference in the structure of the molars of the Cliiro- 
nectes and true Opossums, since the latter animals present 
two longitudinal series of tubercles; beyond this it does not 
appear that there is any difference in the structure of the 
teeth of the animal under consideration, and the species of 
DideljyJnjs , unless it be in the last upper time molar, which is 
compared to the tuberculous molars of the true Carnivora — 
teeth which differ very much in different species of that 
group. With regard to the number of the teeth, which we 
find in the animal examined by Mr. Ogilby was less tlian 
in the Opossums, it is necessary to observe, that such a 
difference might arise from a difference of age; and on this 
point I have to remark, that the Yajwck, upon which the 
foregoing notes were drawn up, was inferior in size to others 
brought to Europe by Dr. Natterer, and that that gentleman 
informed me it was a young animal. Now, we know that in 
Opossums which have nearly attained their full size, but 
which are still immature, the hindermost molar tooth, on 
either side of the jaws, is but partially developed, and, were 
the skin not removed from the skull (as I suspect was the 
case in the Yapock described by Mr. Ogilby). would not be 
