332 BIOLOGICAL LABORATORY OP SYDNEY UNIVERSITY, 



system coincide exactly. In the reproductive oi'gans there are 

 certain differences ; but as none of my specimens had the ovaries 

 ripe it will be necessary to obtain further material before coming 

 to a decision on this point. 



5. " Aquatic Respiration " in Fresh Water Turtles. 



Simon H. Gage (1) announced in 1883, that he had observed 

 the Soft-Shelled Turtle of the United States (^Aspidonectes 

 spinifer), to be in the habit, when lying at the bottom of a tank, 

 of taking water into the pharynx and expelling it again at 

 regular intervals. The very same process takes place in the 

 common Australian Long-Necked Fresh-Water Turtle (Chelodina 

 longicoUis) which has recently been figured and re-described by 

 McCoy. (2) At more or less regular intervals the floor of the 

 mouth is depressed, exactly, as remarked by Gage, by the same 

 movement as that observed in the Frog in breathing air ; the loose 

 walls of the pharynx swell out, and after a short interval the 

 hyoid bone and the floor of the buccal chamber are raised again. 

 A careful observation showed that these movements are accom- 

 panied by the alternate inhalation and exhalation of a considerable 

 volume of water as evidenced by the movements of floating 

 particles, and the question at once arises — Is this a form of 

 auxiliary respiration by means of which the blood of the reptile is 

 aerated during its prolonged immersions in pursuit of food 1 In 

 the case of the American species Gage answers this question in 

 the atfirmative, and bases his conclusion mainly on the presence, 

 as observed by Agassiz, of a series of papillae on the walls of the 

 pharynx, and on the relatively small lung-capacity of the species. 



Neither of these conditions hold good in the case of the 

 Australian species. The pharynx is lined by a perfectly smooth 

 mucous membrane which is not in any high degree vascular, and 

 is clothed with a fairly thick stratified epithelium : while the lungs 



(1) " Proceedings of the American Association for the Advancement of 

 Science," August, 1883. The communication is quoted in full by W. K. 

 Parker. ("Mammalian Descent," pp. 56-58.) 



(2) " Prodromus of the Zoology of Victoria." 



