MO AnatomicaL(^hscrratiGns an 



pha2T.J.^ ; for it is fixed by its base to tbe broad piccC of fTvc" 

 OS hvoides. When the latter then is drawn downwards, 

 whiie the muscular fibres of the tongue at the same time 

 contract, it forms itself into a ball, and, being drawn back- 

 wards by tbe muscles of the os hyoidcs, it necessarily car- 

 vies with it in the. contrary movement the aliments compre- 

 hended between it. and the palate. 



The OS h\-oldcs iv'^ composed of three pieces. The largest 

 0*10 metre by 0'07 is carulaginous, and resembles the broad 

 part of a wooden shovel : the posterior bottom is round, and 

 the interior straight. The latter is inflected on the convex 

 suriacc of the large piece, and it is in the groove formed by 

 this inflection that the root of the timgue is inserted. It 

 results from this disposition that the large piece projects 

 beyond the root of the tongue by about a centimetre. This 

 projectino; edge or kind of ridge becomes a veium, which, 

 when the os h\oides is carried backwards, closes the whole 

 of the back part of ihc mouth, and sometimes also the 

 posterior apertures of the nostrils. 



Such is the mechanism which allows the crocodile when 

 pursued and iVi>ihtened, as I have had occasion to observe 

 in Upper Egypt, to shelter itself, and to lie concealed in 

 the river, and to be able to respire in it. It only thrusts out 

 of the water the extremity of its muzzle where the nasal 

 apertures are situated : the jaws are then open, without the 

 water being able to penetrate into the tesophagus and tra- 

 chea. 



Tlic horns of the os hyoidcs are two small arched and 

 elongated bones about 0-07 metre in length. 



The OS hyoidcs is drawn backwards by four muscles, the 

 exterior ones of which arc round and the interior fiat : it is 

 drawn forwards by the contraction of the tongue. 



Perrault gives to the (ssophagus of the young crocodile 

 which he exiunined a sfreater diameter than to the stomach, 

 lie compitres the oesophagus of this reptile to the gizzard 

 <jf a bird which feeds on iirain ; and he consequently sup- 

 poses, what would be an anomaly too monstrous to be found 

 in the animal ceconomy, that digestion is effected in a great 

 measure in the -psophagus. My observations are directly 

 contrary to those of that celebrated anatomist. I found the 

 diameter of the oesophagus to be ()-0G metre, and that of the 

 stomach ()-!7 by 0-1.5 ;"for the form of this bag is that of 

 an ellipsoid slightly compressed on the sides : in a word.^ 

 it did not appear to me to have any resemblance to a gizzard. 

 The veivetv tunic was exceedingly thick ; the muscidar part 

 was less su : the inside was lilled with a quantity ot smaM 



pebbles. 



