* 



A N A 'I" O -M Y A N I) P 11 Y S I L Q Y O V 



the flesh} tongue is applied to the posterior naves so as to close them, and the 

 mylo-hyoid floor of the mouth contracts, to force the imprisoned air into the lung. 

 A succession of such acts fills it. 



Before entering upon the details of description, it may he well to premise, that 

 tins anatomical section of OUT paper is intended mainly as an exposition of the 

 muscular and neural apparatus by means of which the movements of air to and 

 from the lungs are effected in chelonians, and while, to rend< r the subject more 

 inteUigible, we shall rehearse the general anatomy of the organs of respiration, we 

 shall avoid all questions of structure or function irrelative to the point of inquiry, 

 referring the reader desirous of such knowledge to the more general works on 

 comparative anatomy. 



Underlying the floor of the mouth, and embracing with its cornua the sides of 

 the pharynx posterior to the jaw, is the hyoid apparatus, or the tongue-bone, Fig. 1, 



Fig. 1. 



(( 



£^~ 



p r, |. ,,, ,,', lesser cornua; b, b\ greater cornua; r, c', cartilaginous processes; d, il\ ossicles for attachment of 

 suspensory ligaments; e, body of bone ;_/', fenestrum, closed by cartilage; g, articulations of cornua with body. 



an instrument conspicuous for the part it has evidently played in fixing upon its 

 possessor the batrachian type of respiration. It consists of an elongated body, 

 excavated for the lodgment of the larynx and upper rings of the trachea, and of a 

 cartilaginous process and two bony cornua on each side, connected with it by mova- 

 ble articulations. To the extremity of the anterior or major cornu is attached a knob 

 or ossicle, for tin- reception of the suspensory ligament. This ligament arises from 

 the mastoid process of the temporal hone of the cranium, and forms the fulcrum on 

 which the apparatus swings backwards and forwards, moved by alternate contrac- 

 tions of the genio-hyoid and omo-hyoid, and other muscles of the neck. The hyoid 



