318 mr. g. e. dobson on the [May 1 9, 



face. Having accomplished this it remained tranquil, resting on 

 the upper surface of the net. 



The same fish was, on the following day, replaced in the same jar 

 and the net strengthened. The animal remained tranquil for five 

 minutes, then became uneasy and dashed about violently, several 

 bubbles of air passing upwards from the gill-openings. Occasionally 

 it would remain quiet at the bottom for one or two minutes, then 

 become very uneasy, and struggle powerfully against the net. Half 

 an hour after immersion the fish became even more energetic in en- 

 deavouring to break the net, but soon became weaker, and died in 

 1 hr. 10 min. 



Repeated the same experiment with three smaller-sized specimens 

 of the same species. Immediately after the diaphragm had been 

 fixed the fish rose and attempted to reach the surface, striking vio- 

 lently against the net. They then sank to the bottom, and during 

 the first half hour frequently renewed their attempts to reach the 

 surface. One of the fishes thrust its head through one of the meshes 

 of the net and was retained in that position. The other two died at 

 the same time, in 1 hr. and 5 min. (lying at the bottom in 10 inches 

 of water) ; the third fish (which was retained in the mesh of the net 

 near the surface, above which it did not, however, get its mouth) 

 died twenty-five minutes afterwards. 



The experiment was again repeated. Two specimens of the same 

 species were placed in about 6 inches of water, with a perforated 

 metal plate half an inch beneath the surface. They struggled in 

 precisely the same manner, and then lay at the bottom for some 

 minutes, the gill-covers moving slowly and with difficulty. Struggled 

 violently one hour after the diaphragm was fixed, and died in 1 hr. 

 35 min. 



Exp. 10. — A specimen of Ophioeephalus punctatus, 4 inches in 

 length, was placed in the same glass jar at 1 .55 p.m. ; at 2.10 p.m. it 

 rose towards the surface and pushed against the net ; at 3.30 p.m. it 

 feebly endeavoured to reach the surface, but soon sank down ex- 

 hausted. Respiration appeared to have entirely ceased; a large 

 bubble of air passed upwards from its mouth ; and it died three 

 minutes afterwards. 



Another specimen of the same species was subjected to the same 

 experiment. The fish became much excited after being placed in 

 the water, aud swam about rapidly, striking against the netting for 

 about two or three minutes. It then sank to the bottom and remained 

 quiet. On being roused up ten minutes afterwards it again rose and 

 made many energetic attempts to reach the surface, during which 

 a bubble of air escaped from its mouth. It again sank to the bot- 

 tom and remained there, the gill-covers moving very slowly. Death 

 occurred in 4 hrs. 40 min. The mouth was widely opened towards 

 the time of death. 



Exp. 11. — At 11 a.m. placed a specimen of Mastacembelus pan- 

 calus and one of Rhynchobdella aeuleata in the glass jar, fixing the 

 netted diaphragm as in preceding experiments. Both the fishes made 

 several attempts to reach the surface ; the R. aeuleata nearly sue- 



