2828 THE BONY FISHES AND GANOIDS 



Argentina and Uruguay, growing to a length of six or seven feet, and having the 

 yellowish skin marked with a number of black spots, like a hunting leopard. 

 Somewhat curiously, this genus is represented by two outlying species from West 

 Africa. The best-known representative of the fourth and last group of genera in 

 this subfamily is the bay ad (Bagrus bay ad) of the Nile; the group being easily 

 recognized by the circumstance that while the two pairs of nostrils are remote from 

 one another, the hinder have barbels. Both species are confined to the Nile, but 

 the allied Chrysicthys ranges over all tropical Africa, and Macrones and Rita are 

 Oriental forms. In these forms the short dorsal fin has a pungent spine, and the 

 head and neck are generally protected by a tuberculated bony shield. 



On account of the property from which they derive their name 

 eC Catfishes ^"^ mention must be made of the electric catfishes (Malapterurus) 

 of tropical Africa, belonging to a subfamily in which the rayed dorsal 

 fin, when present, is short and confined to the hinder region of the body, while the 

 pelvic fins are inserted behind. From their allies these fishes are distinguished by 

 the total absence of the rayed dorsal, so that they have only a fatty dorsal imme- 

 diately in front of the tail (which is rounded), and opposite the anal. The head 

 and body are smooth, the pectoral fins have no spine, and there are six barbels. 

 The species inhabiting the Nile grows to about four feet in length. 



The only other members of the family, which space admits of men- 

 C tfi h tioning, are the mailed catfishes (Callichthys, Loricaria, etc. ), consti- 

 tuting a subfamily mainly confined to tropical and South America, 

 although represented by a few Oriental forms. In all these fishes there is always a 

 rather short rayed dorsal fin, beneath or in front of which the pelvics are generally 

 inserted. The gill membranes are confluent with the skin of the isthmus, and the 

 gill openings constricted to small slits. The pectoral and pelvic fins are placed 

 horizontally; and the vent is in front of, or only slightly behind, the middle of the 

 length of the body. Among these fishes the species of the genus Callichthys, 

 which are confined to the rivers on the Atlantic side of South America, belong to a 

 group characterized by the nearness of the two pairs of nostrils, between which 

 there is generally a short flap, and by the expansion and reversion of the lower lip 

 to form a broad flap more or less deeply notched in the middle. In the genus 

 mentioned, the head is covered with bony plates, and the body incased in two rows 

 of transversely elongated overlapping shields on each side; all the species being of 

 small size. Like certain other South-American forms belonging to another sub- 

 family, of which the members of the genus Doras are perhaps the best known, 

 these mailed catfishes are in the habit of making nocturnal journeys during the hot 

 season, when the pond they inhabit is about to dry up to another of greater 

 capacity, and they likewise construct nests for their eggs. In the case of the genus 

 last mentioned, these journeys may occupy several nights, during which the fish 

 travel in large companies. As they have no special breathing sacs, they must 

 apparently close their gill openings, and thus keep the gills moist. The nests 

 which are made at the beginning of the rain}' season, are formed of leaves, beneath 

 which the eggs are deposited and watched over by both parents; the whole structure 

 being sometimes placed in a hole on the margin of the river or pond. In the 



