2 | A N A T I > M V A .VI) I'll V S I LOGY OF 



When a turtle of any kind is observed with care, it will bo seen that it breathes 

 at verj irregular intervals. These are much prolonged when it is in the water, and 

 halt an hour or more may elapse before it rises to the top, to take two or three 

 respirations, preparatory to a second plunge. When, during summer weather, the 

 snapping turtle was placed on a table, and observed in air, its respiration averaged on.' 

 to every two minutes and a half, although certain individuals breathed more rarely, 

 and all irregularly. The box turtle breathes still less frequently. A huge snapper 

 observed for some time, gave the following record: — Ten respirations were noted 

 with the intervals between them, which were as follows: — 1, '2, 1, \, 5, |, 1, 4. :). 

 2, f, minutes respectively. In another the respirations during an hour were at 

 almost perfectly regular intervals of two minutes. The size of the turtles did not 

 Mem to bear any notable relation to the number of respirations per minute. 



During the respiratory act in the snapping turtle, ('. serpentina, the box turtle 

 Cistudo Virginea, the green turtle Chel. mydas, and several Tun (he, we have noticed 

 carefull) the exact details of the motions of the various parts. The head and neck, 

 the flank spaces in front of and behind the limbs, these themselves, and the mouth. 

 glottis, and hyoid apparatus, have been scrutinized with care in hundreds of instances, 

 and with these results. 



Turtles breathe easily with the mouth open or shut. This fact alone deprives 

 their respiration of all resemblance to that of Batrachians. 



The respiratory process is threefold, and consists of — 



1. Complete expiration. 



2. Complete and very full inspiration. 



:'». An appearance of slight, or partial expiration, followed by a pause of greater 

 or less duration. 



During the period which precedes this series of movements, the turtle being 

 at rest, the spaces between the posterior members and the plastron and carapace 

 are nearly level, or only a little concave. The shoulders are pushed forward 

 somewhat, the lungs being full at this time, while the large hyoid apparatus 

 is usually dilated or drawn backwards and downwards. Sometimes it is in 

 continual motion, like that of the frog when breathing, but in the turtle this 

 rise and fall of the hyoid arches has no essential connection with that function. 

 When, during the inter-respiratory pause, we open the jaws the same move- 

 ments of the hyoid apparatus may still be seen, nor is it easy at these times to 

 assign to them any very obvious purpose. The glottis may be seen at rest, as a 

 linear slit, Fig. 7, A, in the centre of an ovoidal slightly elevated mound, just back 

 of the tongue, on the floor of the mouth. The first respiratory act is one of expi- 

 ration. Whether the mouth be opened for observation or not, the following move- 

 ments incur: The hyoid apparatus descends and broadens laterally especially at its 

 posterior part, carrying the glottis back and a little down. The object of this action 

 we suppose to be, the separation of the glottis from contact with the roof of the 

 mouth, in order that the air may the more; readily enter it after passing through 

 the nares. At the moment of beginning to expire the glottis opens wide, so as to 

 form a rhombic figure (Fig. 7, 15.) It remains thus until the whole respirator} act 

 is completed. Meanwhile, during expiration the limbs fall in towards the shell 



