PARENTAL CARE AMONG FRESH- WATER FISHES. 415 



THE PROTOPTERES. 



Of the three described Protopteri the earliest known, Protopterus 

 annectens, has the widest range, extending from the streams of trop- 

 ical Africa, north of the Kongo basin, and from near the west coast 

 to the Nile. Protoptems cethioplcus is a species of the \Vliite Nile, 

 and Protopterus doUoi of the Kongo River. The last is distin- 

 guished for its slender bod}^ and many ribs (54) thus simulating the 

 Lepidosireii. 



The Protopteres live mostly in shallow, muddy waters or sw'amps 

 which dry up during the rainless season. They s^^end most of the 

 time at the bottom, and in an acjuarium one may " seek the darkest 

 corner " and squeeze itself " along one of the perpendicular angles 

 of the case." At length it will arouse itself from this lethargy and 

 move about for exercise or for food. J. G. AVood (1803) was " much 

 struck with the exceeding grace of its movements, which indeed very 

 strongly resemble those of the otter." During its progress " the 

 peculiar screwlike or spiral movement of the limbs is well exhibited." 



The open air has to be resorted to more or less for respiration. 



Fig. 7. — Protopterus annectens. After Lankester. 



McDonnell has recorded his experience with the fish. "At first it 

 used to come to the surface for air every three to five minutes, and, 

 taking it in with open mouth, siidv from the surface; small bubbles 

 then generally escaped from the gill apertures, and frequently, before 

 again coming up for more air, a large quantity was expired, bubbling 

 up from the branchial outlets." That the fish " has the power of 

 voluntarily closing the opercular opening was proved by the follow- 

 ing maneuver." " The animal, burying its nose in the fine gravel in thc^ 

 bottom of the vessel, used rapidly to gulp up the gravel and throw i* 

 out through the gills wdth a strong stream of water. It could at will 

 vary this operation by throAving the jet from the right or left aper- 

 ture." After the owner had the animal '' for some months," howevei-, 

 " and it had again become used to the aquatic respiration, it did not 

 come to the surface for air oftener than from ten to twenty minutes." 

 As the water disappears, the fish burrows into the mud, contracts 

 the body, and secretes a great quantity of mucilaginous matter which 

 forms a cocoon around it, and thus it may remain interred initil 

 future rain dissolves the mass and liberates it. But provision is made 



