PECULIAR ORGANIZATIONS. 
*42 
III. As a particularity, yet appertaining to more species 
than one, and also as strictly mechanical; we may notice 
a circumstance in the structure of the claws of certain 
birds. The middle claw of the heron and cormorant, is 
toothed and notched like a saw. [PI. XXV. fig. 1.] 
These birds are great fishers, and these notches assist 
them in holding their slippery prey. The use is evident; 
but the structure such as cannot at all be accounted for 
by the effort of the animal, or the exercise of the part. 
Some other fishing birds have these notches in their bills; 
and for the same purpose. The gannet, or Soland goose, 
has the edges of its bill irregularly jagged, that it may hold 
its prey the faster. [PI. XXV. fig. 2.] Nor can the struc¬ 
ture in this, more than in the former case, arise from the 
manner of employing the part. The smooth surfaces, 
and soft flesh of fish, were less likely to notch the bills of 
aaimals are born prematurely, and in a very imperfect and unformed state; 
and the pouch of the parent seems properly intended for a residence during 
the completion of the process of developement. The kangaroo is an in¬ 
stance of this kind. When full grown it is six feet in extreme length, 
and weighs an hundred and fifty pounds. When born it is only one inch 
in length, and weighs but twenty grains. The fore legs are scarcely dis¬ 
tinguishable, and the hind ones, which in the adult state form half the 
length of the body, are marked only by slight projections at the parts 
where they are afterwards to grow. In fact the kangaroo at birth is as 
imperfectly formed as the young of any other animal would be when but 
a quarter part of the proper period of its growth within its parent had 
elapsed. 
It is remarkable that it has never yet been ascertained whether these 
little embryos are conveyed by the parent animal, or whether they find 
their own way, into the pouch. Having scarce the exercise of any of the 
senses, and being without limbs, it seems almost impossible they should 
make their way there by their own exertions. However this may be, 
they are found in the pouch closely attached, and as it were glued to the 
nipples, by the mouth or rather by that aperture which afterwards be¬ 
comes a mouth. Here they remain, never quitting their hold, until a 
sufficient period has elapsed for their growth to be completed, and they 
have thus arrived in regard to form and structure upon an equality with 
other animals at the usual period of birth. When this is accomplished, 
they undergo, ns it were, a second birth, and emerge from the pouch: but 
return occasionally for the purpose of feeding, and for that of protec¬ 
tion from danger. 
No marsupial animal was known before the discovery of America, of 
which the opossum is a native; and this animal was at first almost regar¬ 
ded as a sort of exception to the laws of nature; since the discovery of 
New Holland, however, and the investigation of its natural history, it 
has been found that the marsupial animals, so far from forming an excep¬ 
tion to the general construction of animals on that continent, constitute 
the prevailing model. With a very few exceptions, all the native animals 
of New Holland are of the marsupial tribe.— Ed. 
