462 Mr. Moncaw's Description of the Anatomy 
mammary organs of the young animal, which died about two 
months after it had entirely quitted the pouch, and at an earlier 
age than any I had previously examined. On opening the 
pouch after death, I found that not one of the four future teats 
was to be discovered (Fig. 1.), but that four distinct follicular 
apertures occupied the situation in which the nipples are 
afterwards found to protrude: from this circumstance I had 
no doubt that not only the lower, but the upper teats also, 
of the kangaroo were originally formed from the eversion of 
follicular canals, of which the external apertures were thus ex- 
posed, and that consequently the analogy which I had drawn 
between the superior teats of this animal and the supernumerary 
nipples of other quadrupeds, was applicable to their functions 
only, and not to any similarity in their structure and develop- 
ment. 
The fact that all the four teats in the kangaroo are formed 
in precisely the same way, was clearly proved by a dissection 
of the mammary glands in the young animal before me ; for on 
tracing the course of the upper follicular openings, I found in 
them an exact correspondence with that peculiarity of structure 
which I have already described as existing in the lower mammae 
previous to the appearance of their nipples (Fig. 2.). At 
this early period of life, however, it will be seen that the four 
glands are of nearly the same size, and that they have not yet 
acquired sufficient magnitude to envelop completely their mem- 
branous canals. | 
It appears then from this dissection and from my former one, 
that the young of the kangaroo at a very early period of life is 
devoid of any external mammary organs ; that their first appear- 
ance is shown in the development of the two superior and appa- 
rently supernumerary and useless teats ; that subsequently the 
inferior teats are protruded from their respective glands, and 
that 
