514 FISHES. 



a length of 2 to 3 feet. It has extraordinary vitality, surviv- 

 ing 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 mouth- 

 fuls 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 inches, coils itself up, 



e.br 



pc. I. 



FIG. 174. Head region of Protopterus. (From W. N. PARKER.) 



sn.t., Sensory tubes ; /./., lateral line ; e.br., external gills ; pc.L, 

 pectoral fin ; op., operculum. 



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 



