Zool.— Vol. I.] RITTER—DIEMYCTYLUS TOROSUS. 79 



is striking indeed. I am convinced that the full-grown 

 males remain in the water during the winter and spring for 

 months together, without ever once leaving it. This I con- 

 clude, chiefly from constant observations throughout the 

 year on the inhabitants of the Alameda Water Company's 

 reservoir at North Berkeley. 



The animals live here literally in thousands, and conse- 

 quently a most excellent opportunity is afforded for study- 

 ing them in nature. Not only do they not leave the water 

 during long periods of time, but they are capable of re- 

 maining for considerable intervals beneath it. 



I have watched several specimens get along at least for 

 half an hour without coming to the surface ; and one in- 

 dividual remained at the bottom of a shallow pool in Straw- 

 berry Creek a full hour after I began to watch him before 

 he came up "to blow." 



(a) Respiration. — There can belittle doubt, I think, that 

 pharyngeal respiration takes place here as Gage has shown 

 to be the case in D. viridescens and various other Amphibia. 



The movements of the pharyngeal parts are apparently 

 less conspicuous in torosus than in viridescens, but they are 

 none the less certain and constant. 



The whole floor of the mouth within the boundary of the 

 lower jaw, and of the neck, is very gradually depressed 

 for a few seconds, then with a sudden twitch, accompanied 

 by a slight but instantaneous opening of the mouth, the de- 

 pressed parts are contracted, and the water which was 

 taken in — through the nostrils? — during the depression is 

 forced out. The depression of the floor is ordinarily so 

 slight that it may easily be overlooked. If, however, one 

 is able to watch the animal attentively for some time directly 

 from the side of the head, he will see distinctly enough 

 both the downward and the upward movements of the parts. 

 That water is expelled from the mouth when the twitch oc- 

 curs may be ascertained by carefully watching any fine par- 

 ticles of solid matter, such as powdered carmine, that may 

 be suspended in the water in the immediate vicinity of the 

 mouth. The jet, or current of expelled water, is not directed 



