ACTION OF THE CARNIVOROUS WATER-BEETLES. 



179 



varied from 8 seconds to 150 seconds. The time it was exposed 

 for breathing bore to the time it was not so exposed a ratio of 

 1 : 19y'^)•. The species was observed twice at night, but appeared 

 to be scarcely more active than during the day. 



Xiy. AciLius suiiCATtrs, var. 



No. 1. Sept. 19th, 1875. — A female specimen, rather immature, 

 fasting. Observation commenced at 3.36 p.m.. 



Observation ceased at 4.36. The instantaneous breathings 

 were performed by rising to the surface, opening wide the breath- 

 ing-crack and instantly descending; bubbles of gas escaping from 

 the extremity during descent. 



No. 2. Sept. 20th. — By lamplight ; observation commenced at 

 8.42 P.M., when the following times of ascent for aeration were 

 observed : — 



