172 On the Natural History of the Dugong. 
lip,*) that this may not improbably be a mere sexual distinction. 
Amongst the mammalia it is undoubtedly a general law, that the fe- 
males are less developed in numerous portions of the body than the 
males,—a principle which, in many instances, extends itself to the 
teeth. Thus, the canine teeth in the musk-deer are much shorter, 
thinner, and straighter in the male than in the female, in which, 
indeed, they are sometimes altogether wanting. ‘Thus also in the 
horse genus, the canines are almost always wanting in the female ; 
and thus (to return to our own cetacea) the female narwhal often 
has a very inferior developement of the horn which at other times 
renders her undistinguishable from the male. t 
Do not the foregoing statements, then, authorize the following 
results ? 
1. The specimens which have been described in the text, are 
of the full grown animal,—the ordinary length of the adult 
dugong being between 8 and 9 feet. ¢ 
2. The number of molar teeth varies from five in youth, to 
three, and, according to Cuvier, even to two, in maturity, 
on each side of each jaw. 
3. The inferior incisives have not been observed to attain a 
developement fitting them for use. 
4, The superior rudimentary incisives are cast in youth and 
never replaced. 
5. The peculiarities observed in the structure, size, and form 
of the tusks, are indicative of sexual differences,—the tusks 
of the female probably never projecting sufficiently for use. 
They certainly are not the characters of age; and there 
seems to be no reason to believe that they point out distine- 
tions of species, or varieties. 
It was my purpose to have subjoined to this memoir a tabular 
view of the comparative dimensions of the different crania, with a 
plate containing figures of each ; but superior power has prevented 
my design. I trust, however, that when science is freed from mo- 
nopoly,—when the gates of knowledge are no longer infested by a 
preternatural Cerberus, (whatever may be the sop that shall stupi- 
fy his vigilance,) I shall be able to effect the completion of this 
subject with that degree of success which my means will permit. 
* See Mr. Corse’s Obs. on the different species of Asiatic Elephants, Phil. 
Trans. 1799, p. 208. In the Barclayan Museum, belonging to the Royal Col- 
lege of Surgeons of Edinburgh, (from the use of which the public are fortu- 
nately not debarred, ) there is a noble specimen of an old female elephant, brought 
by Dr. Ballingall from Asia. The imperfect state of dentition in the tusks of 
this ee forms an interesting corroboration of the above views. 
+ Lesson Cétacés, p. 108. 
+ Sir Stamford Raftles observes, ‘ they are seldom caught above 8 or 9 feet 
in length, but how much larger they grow is not ascertained, as when they ex- 
ceed this size, their superior strength enables them to make their escape when. 
attacked,” Phil. Trans. 1820, p. 180. 
