COMPARATIVE ANATOMY, 
transverse slit new' tlie foramen incisivuni, 
of which Fallopius gave the following accu- 
rate account in tire year 1561 : “ I find this 
division to be rather a slit than a suture, 
since it does not separate one bone from 
the other, nor does it appear exteriorly, nor 
join two bones, which is the office of 
sutures.” “ Obs. Anat.” 
Hence I was much surprised to find Vicq 
D’Azyr in 1780, discover in this point an 
imexpected resemblance between the cra- 
nium of the human subject, and of quad- 
rupeds. “ Mem. de I’Acad. des Sc. 1780. 
In the celebrated dispute of the 16th cen- 
tury, whetlier Glalen’s osteology was deriv- 
ed from the skeleton of man or the ape, 
Ingrassias argued for the latter side of the 
question from Galen’s having ascribed an 
intermaxillary bone to the human subject. 
And the same author, in his classical “ Com- 
mentarii in Galeni Librum de Ossibus,” 
Panorm, 1603, fol. particularly points out 
the parts, “ where Galen, led astray by the 
dissection of apes, deviates from the true 
construction of the human body.” 
In mammalia, which have horns, tliese 
parts grow on particular processes of certain 
bones of the cranium. In the one-horned 
rhinoceros, they adhere to a rough and 
slightly elevated surface of the vast nasal 
bone. The front horn of the two-horned 
species has a similar attachment ; the pos- 
terior rests on the os trontis, as those of the 
horned pecora do. Two kinds of structure 
are observed in the latter : there are either 
proper horns, as in the genera of tlie ox, 
goat, and antelope ; or bony productions, 
as in the genus cervus, which includes ani- 
mals of the deer kind : these are also called 
horns in English, or sometimes antlers ; in 
French, bojs de cerf. In the former, the 
external table of the frontal bones is elon- 
gated into a process, which contains a con- 
tinuation of the frontal sinuses, except in 
the antelope. Its external vascular surface 
secretes the horn, which covers tliis process 
like a sheath. In the stag kind (in the male 
only in most genera), the frontal bone 
forms a short flattened prominence, from 
which the proper antler immediately shoots 
fortlj. It is renewed every year, and is 
covered, durmg the time of its growth, with 
a hairy and very vascular skin. 
Castration, or any essential injury of the 
organs of generation, impedes the growth, 
alters the fotnif or interrupts the renewal 
of the horns. 
The word horn, which is frequently ap- 
plied in English to the antlers of the deer 
kind, as well as to the real horns of othef 
genera, would lead to a very erroneous no- 
tion on this subject. The antler is a real 
bone ; it is formed in the same manner, and 
consists of the same elements as otlier 
bones ; its structure is also the same. 
It adheres to the fi-ontal bone by its 
basis 5 and the substance of the two parts 
being consolidated together, no distinction 
can be traced, when the antler is com- 
pletely organized. But the skin of the fore- 
head terminates at its basis, which is mark- 
ed by an irregular projecting bony circle ; 
and there is neither skin nor periosteum on 
the rest of it. The time of its remaining on 
the head is one year : as tlie period of its 
fall approaches, a reddish mark of separa- 
tion is observed between the process of the 
frontal bone and the antler. This becomes 
more and more distinctly marked, until the 
connection is entirely destroyed. 
The skin of the forehead extends over 
the process of the frontal bone when the 
antler has fallen : at the period of its rege- 
neration, a tubercle arises from this process, 
and takes the form of the future antler, be- 
ing still covered by a prolongation of the 
skin. The structure of the part at this 
time is soft and cartilaginous ; it is imme- 
diately Invested by a true periosteum con- 
taining large and numerous vessels, which 
penetrate the cartilage in every direction, 
and by the gradual deposition of ossific 
matter convert it into a perfect bone. 
The vessels pass through openings in the 
projecting bony circle at the base of the 
antler : the formation of this pai't, proceed- 
ing in the same ratio with that of the rest, 
these openings are contracted, and the ves- 
sels are tliereby pressed until a complete 
obstruction ensues. The skin and perios- 
teum then perish, become dry and fall off j 
the surface of the antler remaining unco- 
vered. At the stated period it falls off, to 
be again produced, always increeising in 
size. 
The skeleton of quadrupeds deviates 
more from that of man, in the form of the 
lower jaw bone, than in any other part. 
This difference consists chiefly in the want 
of a prominent chin ; that peculiar charac- 
teristic of the human countenance, which 
exists in every race of mankind, and is 
found in no other instance whatever. Man 
has also the shortest lower jaw in compari- 
son -with the cranium ; the elephant, per- 
haps, approaching the nearest to him in this 
character. The same bone is further dis- 
tinguished by the peculiar form and direcr 
