No. 469] 



BIOLOGY OF THE DUGONG 



55 



The increase in the length of the intervals between breaths, 

 given above, is of interest. It is of course quite possible that 

 the conditions of living and of breathing incident to the animal's 

 long period of captivity were extremely abnormal, so that it is 

 difficult to learn from them precisely the normal conditions. 

 Nevertheless, we cannot be far wrong if we take as tlic average 

 time between breaths a minute or a trifle less. Tlit' accoiints of 

 writers show great disparity on this point. Ixiippcl stales that 

 the dugongs come to the surface about once a minute. Accord- 

 ing to Klunzinger they do so every ten minutes and always about 

 four times. Semon observed a large male that came up at inter- 

 vals of from three to five minutes, and Finsch agrees as to these 

 longer intervals. However that may be, it should be observed 

 that the longest interval between breaths noted by us did not 

 exceed two and a half minutes. 



The dugongs, as above noted, feed chiefly by tiight and the 

 same is also true of the manatee. 'Vo l)c sure, Noack ('87, p. 

 300) writes that they eat all day long without interruption, though 



Muric. M). |.. L> 1 The uJnl ..ml the feediii- habit, uf th- .hi^ong 



it appears, (hreetly on tht> sea bottom, and with their thick li})s 

 graze leisurely upon the seaweeds (sea alga\ aceonhng to Uuppel) 

 that grow on the rocks or the sea floor, or they tear them from 

 the bottom. Khni/inger speaks of sea i>lant-. phanero-anis 

 (Niadesj. According to Finsch and Semon it is ehielh ^ea ^^ras'^es 

 and species of Fucus, according to Fairliolnie, "lira-^-hke >ea- 

 weeds," that constitute the food supply. Hut it iiiav l)e stated 

 that the food of the dugong does not consist of the thick, dark 

 brown seaweeds floating up free from tlie bottom, but rather of 

 the two green phanerogamous plants which \ven> present in the 

 stomachs of all the dugongs killed, uiunixed with any other vege- 

 table remains. The (higoug (ish<M iiiei) einphiyed by I )e.\h-r paid 

 no attention to the iieds of thick, (hirk hrowii >eawce(ls that could 



