174 MR. D. SHABF ON THE EESPIBATORT 



Summary. — This species rose to breathe on the average once in 

 10| minutes, and remained on an average about 8| seconds for 

 each, respiration, this period varying, however, from 1 second to 

 22 seconds ; the time it was exposed for this purpose bearing to 

 the time it was concealed a ratio of about 1 : 765. From one 

 obsei'vation it would seem that the species is more active by night, 

 but a second observation contradicted this ; on this second occa- 

 sion the beetle had, however, fed largely a few hours before, and 

 this might possibly account for the discrepancy. 



X. Laccophilus OBSCIJETJS, Scliaum. 



No. 1. Sept. 19th, 1875. — A female example of this beetle was 

 quiescent at 3.36 p.m. near the surface in a tuft of weed, reaching 

 to the surface ; at 3.89 it quietly ascended the weed to the surface, 

 and, making a very small crack, remained breathing 80 seconds, 

 then quietly descended to its originarposition ; as it descended, a 

 bubble of air was extended, but not detached, till about 3.48, when 

 it v/as detached, and the beetle rose to the surface as before, and 

 remained breathing just as before for 60 seconds. The above- 

 mentioned descent then reoccurred ; at 4.8 the bubble was de- 

 tached, and at 4.9 the beetle breathed for 55 seconds, and at 

 4.33 again for 45 seconds. Except for the slight rises and descents, 

 quite quiescent all the time. Observation ceased at 4.36 p.m. 



No. 2. Sept. 20th. — The same specimen examined by artificial 

 light at 8.42 p.m., when the following ascents and other move- 

 ments were taken cognisance of: — 



Eose at : — 



Observation ceased at 9.42 p.m. The beetle moved about 

 pretty freely in water in a very graceful and perfect manner, 

 having two or three very diiferent motions. In one it undulates 

 slowly through the water (somewhat after the manner of B.ydro- 

 vatus), this being done by paddling with the middle and front 

 legs, while the hind ones are flexed and motionless ; a second 



