166 ME. D. SHAEP ON THE EESPIEATOHT 



that probably the female is even more sedentary than the male 

 and also that perhaps it is more active after dark than during 

 daylight. 



The creature's natural habit appears to be almost constant con- 

 cealment in the soft mud at the bottom of the water ; from this it 

 rises to breathe and descends into the mud with great rapidity. 



II. Htdeovaxus cltpealis. 



No. 1. Aug. 29th, 1875. — This observation commenced at 3.15 

 P.M. The individual, a female, at first was not to be seen, but 

 at about 4.45 was noticed to be walking on the sand at the bottom 

 of the water ; and at 4.50 it ascended towards the surface by 

 crawling up the stem of a plant ; but before reaching the surface 

 it found a bubble of gas adhering to the plant, when it turned 

 round and backed its posterior extremity into the bubble. The 

 observation ceased at 4.55, when it was still in this position. If 

 this observation be correct, the insect was 1| hour without breath- 

 ing ; but it is possible that it may have breathed other gas- 

 bubbles on the plant without being noticed. I do not think, 

 however, such was the case. 



No. 2. Sept. 12th. — From 4.5 p.m. till 5.45 p.m. (namely, in 

 all, 100 minutes) kept watch on a female specimen of S. clypealis, 

 which was concealed under a small stone, and did not emerge 

 during this interval of time. 



No. 3. Same date. — At 9.19 p.m., by lamplight, began watching 

 the above-mentioned § . At 9.24 it was gliding about the sand, 

 and rose for a scarcely appreciable instant, did not breathe, after- 

 wards glided about, and rose at 9.27 for about 3 seconds to take 

 in air ; also at 9.51 for about 3 seconds. The observation ceased 

 at 10.9. 



It is possible that the artificial light interfered with its move- 

 ments ; it was observed to pass over the surface of the sand with 

 a comparatively slow motion which appeared to be running rather 

 than swimming, and availed itself of the side of the glass or some 

 object rising to the surface to guide it up ; it followed up the 

 course of such object with the running motion above alluded to. 



No. 4. Sept. 26th. — No sight of the beetle, which lay concealed 

 under a small stone. Observation from 1.31 p.m. for an liour. 



No. 5. Same date. — Observation commenced at 9.11 p.m, by 

 lamplight. At 9.50 it came out from under a stone, crawled up the 



