Comparative.] ANATOMY. -6 57 
ares have fharp cutting edges, calculated for cutting 
fiefh, and breaking the hardeit bones. 
The tongue, in confequence of the length of the jaws, 
is much longer than ours; and, as this creature feeds with 
his head in a depending pofture, the bolus would always 
be in danger of falling out of the mouth, were it not 
for feveral prominences or .papillae placed moftly at the 
root of the tongue, and crooked backwards in fuch a 
manner, as to allow any thing to pafs ealily down to the 
jaws, but to hinder its return. By the papillae alfo the 
furface of the tongue is increafed, and a ftronger impref- 
fion is made on the fenlation of taite. In lome animals 
who feed on living creatures, thefe tenter-hooks are (fill 
more confpicuous; as in feveral large fillies, where they 
are almoft as large as their teeth in the fore-part of their 
mouth, and nearly as firm and ftrong. When we open 
the mouth of a dog, we fee the amygdalae very prominent 
in the polterior part of it; fo that it would appear affirft 
view, that thefe were inconveniently placed, as being con¬ 
tinually expofed to injuries from the hard fubliances this 
animal fwallows: but, upon a more narrow fcrutiny, we 
find this inconvenience provided againft by two membra¬ 
nous capfula;, into which the amygdalae, when prelfed, 
can efcape, and remove themfelves from fuch injuries. 
The velum pendulum palati is in this creature coniiderably 
longer than in man, to prevent the food from getting into 
his nofe ; which would happen more frequently than with 
us, becaufie of its fituation while feeding. 
In the dog, as well as in other quadrupeds, there is no 
uvula-, but then the epiglottis, when prelfed down, covers 
the whole rima entirely, and naturally continues fo: there 
is therefore a ligament, or rather mufcle, that comes from 
the os hyoides and root of the tongue, that is inferted into 
that part of epiglottis where it is articulated with the cri¬ 
coid cartilage, which ferves to raife it from the rima, tho’ 
not fo firongly but that it may with a fmall force be clap¬ 
ped down again. It may be alked, however, Why the 
uvula is wanting here, and not in man ? This feems to 
be, that quadrupeds, who fwallow their food in an hori¬ 
zontal fituation, have no occalion for an uvula, though it 
is neceffary in man on account of his ere£t fituation. 
, In the upper part of the pharynx, behind the cricoid 
cartilage, there is a confiderable gland to be found, which 
ferves not only for the feparation of a mucous liquor to 
lubricate the bolus as it palfes this way, but alfo to fup- 
ply the place of a valve, to hinder the food from regurgi¬ 
tating into the mouth, which it would be apt to do by 
reafon of the defeending fituation of the creature’s head. 
Inman, this mufcle of the epiglottis is wanting, its place 
being fupplied by the elalticity of the cartilage. The 
■tzfopkagus is formed nearly in the fame way as the human. 
Authors indeed generally allege, that quadrupeds have 
their gullet compofed of a double row of fpiral fibres de¬ 
collating one,another; but this is peculiar to ruminating 
animals, who have occafion for fuch a decuffation of fibres. 
The action of thefe may eafily be obferved in a cow chew¬ 
ing her cud. 
The canine nofe is generally longer than that of man, and 
its external palfage.is much narrower. The internal ftruc- 
ture is alfo better adapted for an acute fmelling, having a 
larger convoluted furface on which the membrana fcheideri- 
ana is fpread; and this is to be obferved in molt quadru¬ 
peds, who have the ollk fponginofa commonly large, and 
thefe too divided into a great number of exceffively fine 
thin lamellae. The fenfibility feems to be encreafed in 
proportion to the furface; and this will alio be found to 
take place in all the other fenfes. The elephant, which 
has a head large in proportion to its body, has the greateft 
part of it taken up with the cavity of the nofe and frontal 
linufes; which laft extend almoft over their whole head, 
and leave but a fmall cavity for their brains. A very nice 
fenfe of fmelling was not fo abfolutely necelfary for man, 
who has judgment and experience to diredt him in the 
choice of his food ; whereas brutes, whoTave only their 
fenfes, nnift of necellity have thefe acute; fome having 
Vgl. I. No. 42. 
one fenfe in greater perfection than others, according to 
their different way of life. We not only conclude, a priori , 
from the large expanded membrana fcheideriana, that 
their fenfe of fmelling is very acute, but we find it fo by 
cows and horfes diftinguifhing fo readily between noxious 
and wholefome herbs, which they do principally by this 
fenfe. 
The external ear in different quadrupeds is differently 
framed, but alw ays calculated to the creature’s manner of 
life. In fhape it commonly refembles the oblique fection 
of a cone from near the apex to the bulls. Hares, and 
fuch other animals as are daily expofed to infults from 
beafts of prey, have large ears directed backwards, their 
eyes warning them of any danger before; rapacious ani¬ 
mals, on the other hand, have their ears placed diredtly 
forwards, as we fee in the iion, cat, &c. The flow hounds, 
and other animals that are deligned to hear tnoft dfttindtly 
the founds coming from below', have their ears hanging 
downwards; or their ears are flexible, becaufe they move 
their head for the mod part with greater difficulty than 
man. Man again, who muff equally hear founds coming 
from all quarters, but efpecially fuch as are fent from 
about his own height, has his external ear placed in a ver¬ 
tical manner, fomewhat turned forward. In fhort, where - 
ever we fee a fpecialty in the make of this organ in any 
creature, we (hall, with very little reflection, difcover 
this form to be more convenient for that creature than 
another. The animal alfo has the power of directing the 
cone of the ear to the fonorous body without moving the 
head. There are fome differences to be obferved in the 
ftrudture of the internal ear in different animals; but we 
know fo very little of the ufe of the particular parts of 
that organ in the human fubjedt, that it is altogether irn- 
polfible to give reafons for thefe variations mother creatures. 
All quadrupeds have at the internal canthus of the eye 
a ftrong firm membrane with a cartilaginous edge, which 
may be made to cover fome part of their eye; and this is 
greater or lefs in different animals as their eyes are more 
or lefs expofed to dangers in fearching after their food. 
This membrana niclitans, as it is called, is not very large 
in the dog. Cows and horfes have it fo large as to cover 
one half of the eye like a curtain, and at the fame time 
it is tranfparent enough to allow abundance of the rays 
of light to pafs through it. Fifties have a cuticle always 
over their eyes, as they are ever in danger of that incon- 
ftar.t element, the water. In this then we may alfo ob- 
ferve a fort of gradation. Quadrupeds have alfo a feventh 
mufcle belonging to the eye, called J'uJp‘ nfonus. It fur- 
rounds almoft the whole optic nerve, and is fixed into the 
fclerotic coat as the others are. Its ufe is to fuftain the 
weight of the globe of the eye, and prevent the optic 
nerve from being too much ftretched, without obliging 
the four ftraight mufcles to be in a continual contradlion, 
which would be inconvenient; at the fame time this muf¬ 
cle may be brought to aflift any of the other four, by cau- 
fing one particular portion of it to act at a time. 
The next thing to be remarked is the figure of the pupil, 
which is different in different animals, but always exadlly 
accommodated to the creature’s way of life, as well as to 
the different fpecies of objects that are viewed. Man has 
it circular, for obvious reafons; an ox has it oval, with 
the longed diameter placed tranfverfely, to take in a lar¬ 
ger view of his food; cats, again, have theirs like wife 
oval, but the longed diameter placed perpendicularly ; 
they can either exclude a bright light altogether, or ad¬ 
mit only as much as is neceffary. The pupil ol different 
animals varies in widenefs, according as the internal or¬ 
gans of vifion are more or lefs acute. Thus cats and owls, 
who leek their prey in the night, or in dark places, (and 
confequently mult have their eyes fo formed as that a few 
rays of light may make a lively impreflion on the retina,) 
have their pupils in the day-time contracted into a very 
narrow fpace, as a great number of rays would opprefs 
their nice organs; while in the night, or where the light 
is faint, they open the pupil, and very fully admit the rays. 
8 E 'In 
