PECULIAR ORGANIZATIONS. 
141 
force of this compression sends out the fluid with a con¬ 
siderable impetus through the tube in the middle of the 
tooth. What more unequivocal, or effectual apparatus 
could be devised, for the double purpose of at once inflic¬ 
ting the wound and injecting the poison? Yet, though 
lodged in the mouth, it is so constituted, as, in its inoffen¬ 
sive and quiescent state, not to interfere with the animal’s 
ordinary office of receiving its food. It has been observed 
also, that none of the harmless serpents, the black snake, 
the blind worm, &c. have these fangs, but teeth of an equal 
size; not movable, as this is, but fixed into the jaw. 
II. In being the property of several different species, 
the preceding example is resembled by that which I shall 
next mention, which is the bag of the opossum. [PI. XXIY. 
fig. 1,2, 3.] This is a mechanical contrivance, most proper¬ 
ly so called. The simplicity of the expedient renders the 
contrivance more obvious than many others, and by no 
means less certain. A false skin under the belly of the 
animal forms a pouch, into which the young litter are re¬ 
ceived at their birth; where they have an easy and constant 
access to the teats; in which they are transported by the 
dam from place to place; where they are at liberty to run 
in and out; and where they find a refuge from surprise and 
danger. It is their cradle, their conveyance, and their 
asylum. Can the use of this structure be doubted of ? Nor 
is it a mere doubling of the skin; but it is a new organ, 
furnished with bones and muscles of its own. Two bones 
are placed before the os pubis, and joined to that bone as 
their base. These support, and give a fixture to, the mus¬ 
cles, which serve to open the bag. To these muscles there 
are antagonists, which serve in the same manner to shut it; 
and this office they perform so exactly, that, in the living 
animal, the opening can scarcely be discerned, except when 
the sides are forcibly drawn asunder.* Is there any action 
in this part of the animal, any process arising from that 
action, by which these members could be formed? Any 
account to be given of the formation, except design? f 
* Goldsmith’s Nat. Hist. vol. iv. p. 244. 
t There is a very considerable number of animals possessed of the same 
structure which is here described as existing in the opossum, to which the 
attention of naturalists has been more particularly called since the first pub¬ 
lication of this work. The animals of this kind are called marsupial, from 
the pouch or marsupium which distinguishes them. This provision also 
lias a relation to circumstances in the reproduction of these animals to 
which Dr. Paley has not referred. He appears merely to regard it as a 
place of refuge and deposit for the young; somewhat in the same way as 
the wings of a hen are for its brood. The fact is that the young of these 
