ACTION OE THE CARNIVOROUS "WATEB-BBETLE3. 17l 



for aeration ; again at 4.34, remaining up for 3 seconds. Ceased 

 watching at 4.41 p.m. 



No. 2. By lamplight, same night at 9.14, when the beetle was 

 under cover. It afterwards made the following ascents : — 

 9.38, up for 32 seconds. 9.55, up for 2 seconds. 



9.55 „ 6 „ 

 9.57 „ 2 „ 

 9.57 „ 8 „ 

 then concealed ; obs. ceas ed 

 at 10.14 P.M. 



It hid itself between 9.44 and 9.52, but during the other in- 

 tervals continued active. 



Minutes Seconds at 



Obs. Spec. of obs. Ascents. suj-face. 



No. 1. 1 60 2 4 



„ 2. 1 60 10 70 



Totals... 2 120 12 74 



Summary. — This species was only observed twice ; and it appears 

 to be much more active at night than during the day ; it rose on 

 the average once in 12 minutes, remaining at surface from 1 to 32 

 seconds, on an average rather more than 6 seconds on each occa- 

 sion ; and the time it was exposed bears to the time it was con- 

 cealed a ratio of about 1 : 97^. 



VII. Htdropobus elegans. 



No. 1, Oct. 12th. — Kept observation on a male of this species 

 for one hour's duration, viz. between 3.41 p.m. and 4.41 p.m. The 

 beetle was active, and on three occasions during its rapid move- 

 ments came to the surface of the water, .bat did not appear to rest 

 there or to take a fresh supply of air. 



No. 2. The same night by lamplight. — 9.14 p.m. began watch. 

 a. elegans was also then active, and rose for the purpose of aeration 

 at 9.49, only remaining up, however, for an instant ; again at 9.55 

 it came to the surface for an instant : 10.14, observation ceased. 



Summary. — Only two observations were made on this species, 

 from which it would appear that the species is a very active one, 

 but breathes seldom and very rapidly. 



VIII. HtDKOPORUS 12-PUSTirLATUS. 



No. 1. Sept. 12th, 1875. — Observation commenced at 4.5 p.m. 

 The beetle rose at 4.58 p.m. for a short time ; it was otherwise 



