PROTOPTERUS. 525 



exclusively carnivorous, and attains a length of 2 to 3 ft. 

 It has extraordinary vitality, surviving severe wounds, long 

 fasting, and desiccation. It appears to be most active at 

 night, and to prefer shallow water, swimming rapidly with 

 powerful tail-strokes, or " walking " slowly along the bottom 

 with its filamentous fins moving alternately on each side, 

 somewhat like the legs of a newt. At short intervals it 

 comes to the surface to take mouthfuls of air, which passes 

 out again through the opercular aperture. 



As the dry season approaches, Protopterus burrows into the earth to a 

 depth of about 18 in., coils itself up, and secretes abundant mucus from 

 its skin glands. This secretion forms a cocoon or capsule, with 

 adherent earth externally, with moist slime internally, and with a lid, 

 on which there is always a small aperture. Thus encapsuled, the 

 animal may remain dormant for many months, e.g. from August to 

 December. " The animal lies coiled up in such a manner that the head 

 lies alongside the base of the tail, which from this point is again bent 

 backwards over the head, so that it covers the head and body like a veil. " 

 The air seems to pass directly from the mouth of the burrow, through 

 the aperture of the capsule-lid (which is produced inwards in a short 

 pipe) to the external nostrils, and thence to the lungs. The nourish- 

 ment appears to be derived from a store of fat deposited in the lymphoid 

 tissue around the reproductive organs and kidneys, and among the 

 lateral muscles of the tail (cf. fatty bodies in caterpillars, amphibians, 

 etc. ). Moreover, some of the muscles are replaced by fat, and others 

 undergo a pathological granular degeneration (cf. lamprey). To a 

 certain extent, therefore, the dormant animal lives on its own tail. It 

 is probable that leucocytes aid in the absorption and transportation of 

 the degenerated muscles (cf. tadpoles). These capsules, with the sur- 

 rounding earth, have often been transported from Africa to northern 

 Europe, without injury to the dormant life within. On emergence the 

 animal makes peculiar sounds, probably due to the forcible expulsion of 

 air from the lungs through the lips. 



A few of the anatomical characteristics of Protopterus may now be 

 noted, following Prof. W. N. Parker. 



The paired fins are filamentous, and seem degenerate when compared 

 with those of Ceratodus, having only one series of short lateral horny 

 rays on the cartilaginous segmented axis. The tail is symmetrical, and 

 ends in a filament, which, like the end of the fins, is often bitten off ; 

 often, however, there is a slight upward bending, which suggests a 

 heterocercal condition. Both tail and fins may be regenerated after 

 serious injuries. 



In the skin are very numerous mucus-secreting goblet cells, and there 

 are also (especially on the snout) multicellular glands, which are absent 

 from most fishes, though common in Amphibians, Reptiles, and 

 Mammals. There is a continuous lateral line, and apart from this there 

 are other integumentary sense organs on the head and various parts of 

 the body. There are taste buds on tongue and palate, olfactory organs 



