TJie Heart of the Sea-Twtle. 307 



each other in structure closely were similar in physiological 

 behaviour. Such however, has been rather assumption than 

 the outcome of careful comparison. 



With the view of discharging this task of systematic 

 physiological comparison, I have, during this past summer, 

 made a large number of experiments on various species of 

 sea-turtles at the Marine Laboratory of the Johns Hopkins 

 University at Beaufort in N. Carolina ; and also a limited 

 number of experiments on the land-turtle. I desire to ex- 

 press my thanks to Dr. Brooks, professor of morphology in 

 the Johns Hopkins University for his kindness in facilita- 

 ting my work. 



The marine turtle has much less vitality than other 

 Chelonians, and suffers, when kept for a few days out of 

 the water or deprived of its proper food. In order that my 

 animals should be in the best possible condition, a matter of 

 special importance in connection with the subject of spon- 

 taneous rhythm, a structure known locally as a " turtle pen" 

 was constructed on the sea shore, of dimensions 12 X 8 X 8 

 feet, admitting water freely, and so placed that the animals 

 were never without a certain amount of water at the lowest 

 tide. As learned from a fisherman who made a specialty 

 of catching sea-turtles, their principal food consists of crabs. 

 Upon such those kept for a few days in confinement were 

 regularly fed. Most of the animals upon which I have 

 worked were not kept in the pen for longer than two to 

 four days. 



According to Holbrook's work on American Beptilia the 

 three species of marine turtle used in my experiments were 

 Chelonia caretta or the Loggerhead, Chelonia imbricata or 

 Hawksbill, and Chelonia mydas or the Green Turtle. 



The conclusions and observations of this paper are based 

 upon prolonged and careful experiments by the direct 

 method on twenty specimens of the marine turtle. 



As in my paper on the heart of the Terrapin, the literature 

 of the subject is pretty folly considered, that part will be 

 omitted in this paper, so that it may be kept as short as 

 possible. 



