159 



as ten hours. Gadow (1909, p. 330) has called attention to the 

 importance of the so-called accessory bladders in water tor- 

 toises as organs for anal respiration and has explained in this 

 way the high vascularity of their walls. By means of oral and 

 of anal respiration turtles may be expected to remain under 

 water much longer than alligators or other like forms, and such 

 seems to be the case, for I know of no evidence to show that 

 any alligators will remain unrestrained under water for ten 

 hours as recorded for turtles. 



Through the kindness of Dr. C. H. Townsend, Director of the 

 New York Aquarium, I was enabled to make observations on 

 the submergence periods of a number of marine turtles. These 

 included the green turtle, Chelonia mydas (Linn.), the hawk's- 

 bill, Eretmochelys imbricata (Linn.), the loggerhead, Caretta 

 caretta (Linn.) and Kemp's turtle, Caretta kempii (Garman). In 

 none of these turtles did I observe a voluntary submergence 

 that lasted over 40 minutes though in the Berlin Aquarium I 

 once timed a loggerhead that remained voluntarily under water 

 for a period of 64 minutes. During much of this time the 

 loggerhead exhibited oral respiration. At the New York Aqua- 

 rium I tested the drowning period of a very active Kemp's 

 turtle and found it to be only a little over an hour and a half. 

 The shortness of this period was probably due to the incessant 

 activity of the turtle whereby it must have used up rapidly its 

 store of oxygen. The voluntary submergence period of over an 

 hour for the loggerhead already noted was associated with general 

 quiescence, a state of affairs that must be characteristic of the 

 months of submergence that occur when water tortoises hiber- 

 nate. 



Whether marine turtles are capable of anal respiration or not 

 I do not know, but some of them certainly employ oral respira- 

 tion and this together with anal respiration is probably what 

 enables turtles in general to remain longer under water than is 

 possible with caymans and with alligators. 



REFERENCES. 



Gadow, H. 1909. Amphibia and reptiles. Cambridge Natural History, 

 vol. 8. 



Gage, S. H., and S. P. Gage. 1886. Aquatic respiration in soft-shelled tur- 

 tles: A contribution to the physiology of respiration in vertebrates. 

 Amer. Nat., vol. 20, pp. 233-236. 



Lumsden, T. 1923. Observations on the respiratory centers. Journ. 

 Physiol., vol. 57, pp. 354-367. 



Lumsden, T. 1924. Chelonian respiration (tortoise). Journ. Physiol., 

 vol. 58, pp. 259-266. 



Parker, G. H. 1922. The breathing of the Florida manatee {Trichechus 

 latirostris). Journ. Mammalogy, vol. 3, pp. 127-135. 



