172 DU. BASHFOKD DEAN ON THE [Feb. 20, 



respiration was found to be as brief as eight minutes. Before 

 rising to the surface tlie fish shows evidence of uneasiness ; it will 

 sometimes "gasp" several times, move backward, bend its head or 

 twitch its fins : it wall then rise to the surface, usually slowly, and 

 " spout," i. e. exhale and draw in a mouthful of air somewhat 

 spasmodically. Sometimes it will make sevei'al gulps ; it will then 

 close its mouth and sink to the bottom. In this process, bubbles 

 always pass out on either side of the head as the fish sinks. In 

 one instance it was observed that the air passed out mainly on the 

 left side, and it was also noticed that the fish will sometimes rock 

 slightly from side to side as it sinks. Sometimes a few moments 

 later a large bubble will issue from the mouth. It was also noted 

 that if the fish becomes excited and shows energetic movement, air 

 Avill be ejected. It may finally be noted that at night the breathing- 

 movements appear more fi'equent than during the day : air was 

 taken in at an interval of foui'teen minutes {cf. Ramsay) : this is 

 doubtless correlated with the more active habit at this time. It 

 may be i-emarked that the air-breathing habit of Ceratodus seems 

 to be closely similar to that of Protopterus. 



In feeding-habits Ceratodus resembles an amphibian. It will 

 snap at the food in a similar way, and shows a movement of the 

 head which is more nearly amphibian than fish-like. On one 

 occasion it bent its head 'to the side very much as would a Sala- 

 mander. It has already been mentioned that Ceratodus is slow 

 of sight ; this is especially evident when food is taken. In some 

 cases food will remain for ten minutes in the water before it is 

 noticed by the fish, stimulation appearing to come rather from 

 the taste-buds than from the eyes. It will " feel " apparently 

 that there is something edible in its neighbourhood and it will 

 gradually move in the direction of the stimulus. It was noted 

 that if an object were placed on the surface of the water at the 

 opposite end of the tank the fish would not rise in the direction 

 of the food, but would grope its way uncertainly along the bottom 

 until it came under the food ; then it would rise to seize it. The 

 fish impresses one as taking its food blunderingly ; it will some- 

 times snap repeatedly before it succeeds in securing the object. 

 It would often seize a mouthful, then eject it, then hunt it up 

 again, mouth it, and finally swallow it. The feeding of the present 

 specimens indicates convincingly that the diet of Ceratodus is, as 

 Margo maintained, a mixed one. Animal food, living and dead, 

 is regularly taken, also vegetables, e. g. lettuce ; and that the 

 latter is actually digested and assimilated seems clear, since it is 

 not to be recognised in the f fecal material. 



In the accompanying figures (text-figs, 53 and 54) the fish is 

 represented in positions both of rest and of movement. In fig. 1 

 the fish appears in a not uncommon pose ; it balances accurately on 

 the pectoral fins and in the aiial region, its trunk somewhat arched 

 upward and the head thrust close to the bottom, the pectoral fin 

 extends sideways in such a way that its postaxial border rests 

 against the bottom. In a somewhat similar position (fig. 2) the fish 



