Encyclopaedia Britannica, or, a Dictionary of arts, sciences, and miscellaneous literature : enlarged and improved. Illustrated with nearly six hundred engravings > Volume 8, ELE-FOR

Chap.
Anatomy- no indance of the contrary j that is, of the lower jaw
u-'Y"""' being longed, and perhaps this ftru&ure would be in¬
convenient, or incompatible with the nature of the ani¬
mal, or its habits and mode of life.
A common error long prevailed with regard to the
motion of the jaws of the crocodile. It was afferted,
that this animal only moved its upper jaw 5 but the
more accurate obfervations of later anatomifts have
proved the contrary, and that the articulations of the
head and jaws of this animal are precifely the fame
as in other quadrupeds. The head is articulated with
the laft vertebra of the neck, and the lower jaw is arti¬
culated with the upper, fo that the former, namely the
lower jaw, only has the power of motion.
All the animals belonging to the order of reptiles,
are not furnilhed with teeth. The tortoiles and fome
lizards, have none. All the fpecies belonging to the
genus rana may be conlidered alfo as having none, the
jaws being only crenulated or notched ; but in other
tribes belonging to this order, the teeth are conical,
as thofe of the crocodile, which are hollow, and filled
with a foft fubfiance •, or recurved, when the extremity
of the tooth turns backward towards the throat, as in the
Indian crocodile", or ftraight, as in moil of the lizard
tribe-, comprefled at the fides, as in the guanaj or
notched, when the fummit of the tooth is truncated and
crenulated, as in the horned lizard.
Tongue.—In almoft all the tribes of animals belong¬
ing to this order, the tongue is peculiarly fitted for
feizing their prey. The form of it varies in all the
families. Another error has prevailed with regard
to the tongue of the crocodile. It was faid that it had
no tongue, but in place of it is furnithed with a ftrong
membrane, which adheres to the two edges of the lower
jaw. Even the obfervations of later naturalifts tend to
confirm this error. Denon, who had numerous oppor¬
tunities of feeing the crocodile both dead and alive, in
its native haunts on the borders of the Nile, believes in
this opinion, that the crocodile has no tongue j but it
does not appear that any accurate anatomical infpeftion
was made, to afcertain this point, or indeed that he was
accompanied by any anatomift at all, by whom alone
the truth or falfehood of the opinion could be invefti-
Tongueof gated. This organ of the crocodile, however, is very
the cioco- large, and even proportionally larger than that of the
f*1k. ox, but it is ftrongly connected with the fides of the
lower jaw;.and being thus fixed or tied down, can¬
not be ftretched forwards, as is the cafe with other
animals.
In fome of the animals belonging to this order, the
tongue is nearly of equal length and breadth. This is
the cafe with the tongue of frogs, tortoifes, the falaman-
der, and the guana.
In fome it is very narrow at the bafe, and divided in
two at the extremity, as in mod of the lizard tribe,
which are thus furnifhed with a bifid tongue.
®fthe cha. But the ftrmfiure of the tongue of the chameleon, is
melcoiv perhaps the molt lingular of any belonging to the order.
It is compofed of a white folid flelh, 10 inches long,
and about three broad. It is round, and flattilh to¬
wards the end ; hollow and open, fomewhat refembling
the termination of the trunk of the elephant. The
tongue is attached to the os hyoides by a kind of trunk,
of the lhape of an inteftine, about fix inches long, and a
3°7
line in breadth. This trunk is furnithed externally Anatomy,
with a membrane, and internally with a foft, but folid "" v~~-'
and compaft, nervous fubftance, which is with dif¬
ficulty divided into fibres. It is by means of this trunk
that the tongue, which is attached to it, is projected
from the mouth. This is done by the extenlion ol the
trunk, and it is again drawn back by its contractile
power. Thefe motions are performed by a kind of
cartilaginous fiilus, to which the inverting membrane
is attached, and over which it is plaited like a filk
flocking on the leg. This flilus is an inch long, and
originates from the middle of the bale of the os hyoides.
In eonfequence of this extenfile and retractile powers
which the tongue of the chameleon poffeffes, it has ob¬
tained the epithet of vermiform, becaufe in thole motions
it refembles thofe of an earth-worm.
There is no great peculiarity about the noftrils ofNoftrils.
any of this order of animals. In general, they are al¬
moft always of a round form. In fome, however,
they are lunulated, or Ihaped fomewhat like a crefcent,
the horns of which are turned backwards. This is the
cafe with the noftrils of the crocodile.
The eyes, as in moft other animals, are placed on Eyes,
the fides of the head ; but in fome they are vertical, or
placed on the top of the head, as in feveral of the toads
and the crocodiles j approximating, when the diftance
between the eyes is very fmall; or protuberant, when
the globe of the eye on each fide forms a confiderable
projection, as in thofe belonging to the genus rana, the
crocodiles, and the falamanders.
The nictitating membrane, which is peculiar to fome
birds, belongs alfo to fome of the animals of this order.
By means of extending this membrane over the eye, the
excefiive brightnefs of funthine, to which many of them,
being natives of warm climates, are expofed, is greatly
moderated, and perhaps this membrane may be ufe-
ful to thofe animals of this order which frequent the
water.
The iris of the eye is differently coloured in the ani¬
mals of this order. In many it is red; in the chameleon
it is of a golden yellow colour.
Externally, the ears of reptiles do not exhibit any Ears,
remarkable peculiarity. The opening is more or lefis
round, and it is ufually covered with a membrane.
There is no external ear, by which the vibrations of
the air might be colleCIed, and conveyed to the fenfe
of hearing ; from which it has been concluded, that
this fenfe is more obtufe than in quadrupeds.
2. The Trunk.—The trunk of the body includes
the neck, the breaft, the back, the ribs, the abdomen,
and the anus ; and fome of thefe parts in different rep¬
tiles, prefent confiderable varieties.
The neck, which unites the head with the trunk, is Neck,
very different in the different tribes belonging to this
order. In all thofe included under the genus Rana
the head is fo clofely attached to the trunk, that the
neck is fcarcely to be diftinguilhed. In others, how¬
ever, it is conliderably elongated, and quite diftinCl, as
in the crocodile and the falamander. The neck is alfo .
pretty long in fome of the tortoifes. Sometimes it is
covered with wrinkles or folds, when the Ikin forms
feveral tranfverfe wrinkles, as in the neck of fome of
the tortoifes.
The breaft or thorax is fituated on the anterior partTSjor&x*
s> <12 °f
ERPETOLOGY.