of a T ORfTTO ITSE.                             267
the Aperture of this third Cavitie went enlarging it felf like the end of
a
Trunm)pet, and had a delicate membrane which fanned it to the Circumfev
rence of the hole.
  Thlofe who have made the Defcription of the Ant-IJles, which of all in
the world has tlie greatelt quamtity of Tortoifesdo fay that they are deaf.
We
have reafon to doubt, confidering the Organs that wt have juf defcribed,
whether thef{C Hitlorians may have vfed all the care neceflary for the being
wvell inftfruaed in this Particular, it being probable that they contented
them
!ek'es vith the conieaure which may be drawn thereupon from the defeEt
of the Ap j turc which thele Animals have in their Ears: Unlefs the Ears
Should be in ITortoifes the fame as the Eyes are in Moles ; that is to fay
they
lmould have Ears without Hearing, as the LVoIes have Eyes with which tle,-
do not See.
  The Obiervation which we have made upon the Tortoife's firring its Neck
to turn it felf vh-en it is on its back, has given us an opportunity of fearching
out the Mufcies which do bend and extend this part. We have firft found
that this Neck has two kinds of Motion, which are each Compofed of flexi-
on and extrentioti.  The firftl Motion is that by which the Tortoift draws
its
Neck and Hlead inwards, or extends it, and makes it to go outwards. Thle
fecond is that by which the Neck being thruft out and extended, is turned
on
all Sides. In the firft kind of motion the Neck is extended when the Mufcles
which. ferve for the diffiereat flexions of the Neck do a& together and
with an Equal force; And it is drawn in with the head by two different
lexions and Extentions of the JVertebrx, one of which is at Top and the
,other at bottom: which gives to the Neck a figure like to that which the
,Neck of a S'van takes when this bird draws its head towards its back. For
tihis reaFon, befides the Mufdes which do turn the Neck every way whea
thruft fortlh,and which are common to all the motions of the Neck, there
are
five particular ones on each fide which 'fringing from the Apophyfis lr;nbar4b
and from the lalt ribbs, do afoend along ttae Vertebrx of the back, andare
im-
ierted in live ditFrent places of the oblique Apoplyfis of the IYerte&r~e
o
the Neck, the lcncflt [cing liftned ncar the head to the body of the
firft Vertebra. - The MufClS which, when they a&t Separately do ferve
for the flexions of the Neck thrumf outward, do fpriig fronm the Vertebra
of the Neck, and are likewife in{erted to its Vertebra. Some taking their
0.
riginal at the body of a Vertebra, are infirted to the Apophyfes of others:
Others proceeding from the Apophyfe5 are joyned to other Apopbhfes;InFomuch
that when the Mufies of one fide do a&L Separately, the flexion is made
on
that very tide ; and when they do adt jovntly \vith an Equall force, the
Extenfion of the whole Neck Enfies, as has been faid.
  When the Head is drawn inward, it finks into a fold of the Skin which is
upoln the ihoulders, which formes as it were a Hood. 'Ii his is done by the
means of a very large and thick Mufcle adhering to the Skin, and which
being faftned to the Spind Apophyfes of the Vertebre, from whence it feems
to
rifl, is folded underneath, covering and enveloping the Aspei-a Arteria and
the (ifop.o)eas. The Different fituations of the Fibres of this Mulcie, which
may mIIake it to paife for an union of foveral Mufcles, do produce the di-
vers folds of this Skin made in form of a Hood, when they do art differently.



FINIS.