CAT-FISHES. 



83 



which numerous species are known, has a wide distribution, being [Case 18.] 



found in almost all tropical countries which are drained by large 



rivers ; some of the species prefer brackish to fresh water, and a 



few enter the sea. Arius latiscutatus (Case 17), from West Africa, 



is one of the largest species of this genus. Pimelodus (Case 18), 



common in South America, also includes some very large species. 



The Electric Cat-fish (Malapterurus, fig. 69) occurs in Tropical 



Electric Cat-risk (Malapterurus). (From Tropical Africa.) 



Africa, and grows to a length of about four feet. The electric 

 organ extends over the whole of the body, but is thickest on the 

 abdomen. The Callichthys of Tropical America (fig. 70) have the 



Fig. 70. 



Callichthys. (From British Guiana.) 



body wholly protected by two series of large imbricate shields on each 

 side ; they construct nests for their ova. The species of Aspredo 

 are inhabitants of the Guianas, and remarkable for their mode of 

 carrying their ova : after having deposited the eggs, the female 

 attaches them to, and presses them into, the spongy integument 

 of her belly by merely lying over them, and carries them until they 

 are hatched. 



