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Show 190G.] AUSTRALIAN LUNG-FISH. 169 (Ramsay), can be touched (Semon). Apt to rest for hours on the bottom, pectoral fins extended at right angles to the body, pelvics parallel with it (Ramsay). Neither diurnal, nor nocturnal, seeking food regardless as to the hour of the day (Semon). Breathing.-Does not open gills when out of water (Ramsay). Rises to the surface to breathe every thirty or forty minutes (Semon), but more frequently at night (Ramsay). Lung especially important when water becomes muddy or foul (many authors). Sounds sometimes emitted, " spouting-," a " groaning sound " (Semon), a " pig-like grunt " (Illidge). Swimming.-Progresses chiefly by " waves of the tail " or " by paddling with pectoral tin alone." When \listurbed "lashes out with its great strong tail, and turning sideways squeezes in between some tufts of grass." "Eel-like in movements"-not apt to swim straight forward; in this event, however, pectorals are used, not caudals (Ramsay). "Swims a short distance with a jerk, when it will rest again " (Semon). Its movements are, however, best described by Semon, after notes made (18U9) upon the present specimens by Arthur Thomson : he distinguishes three kinds of progression-(1) a slow forward movement in which the pectorals play the most prominent part, waving "like a flag in a moderate breeze " ; (2) a rising movement, accomplished almost exclusively by the pectorals, after which the fish sinks slowly to the bottom Triton-like; and (3) a rapid strong swimming, accomplished by the caudal, the pectorals and ventrals being opposed to the side of the bottom, as in the case of rapidly swimming amphibians. Thomson observed especially the fish in a position of rest balancing either on its ventromedian line, or partly lifted up supported on its spread out pectorals, or further lifted or supported by both pectorals and ventrals, the last position having been figured {cf. text-tig. 53, 3, p. 173). This supporting function is particularly emphasised by Semon as a step important functionally in the evolution of the land-living vertebrate limb. Thomson, however, was unable to see the alternate movements of the limbs, which had been described in Protopterus, or an elbow-like bending of the base of the pectoral fin. Food.-Many authors emphasize its vegetivorous habits (Giinther, Spencer) ; Semon, on the other hand, maintained that the food is " essentially animal," the plant-material furnishes but a vehicle for the animal food, and remains, therefore, undigested. Margo, finally, has determined by microscopical examination that in cases where the plant portion of the food-material is undigested in the anterior part of the gut, in its hinder part there is convincing evidence of complete digestion, leading to the conclusion that the diet of Ceratodus is a mixed one. Colour.-" Greenish brown on back, and slaty on belly "-after capture 11 becomes very prettily coloured with red, pink, and violet hues on the abdominal parts," colours which disappear after the death. The surface of the fish is " oily " (Illidge). The present specimens-two in number,-as has already been recorded (P. Z. S. 1898, p; 492), were secured in the Burnet River, Queensland, during the beginning of 1898. They have accordingly been kept in captivity for upwards of seven years *. Two other specimens, however, which were brought from Australia at the same time and which passed into the possession of the aquarium in Paris, lived, it is understood, but a short time. It is stated that on one occasion during the transportation of these fishes suitable tanks could not be procured and that the specimens were sent for a * Purine; this interval they appear to have grown at t lie rate of a little .in inch a year. |