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ward for one with young. Two Platystomas were brought with young, 

 but instead of being the young of the giant catfish, he found that the 

 small fishes were the types of a distinct parasitic or commensal fish, 

 which he called "Stegophilus insidiosus." 



It is certain that some members of the Stegophilini live in the open, 

 very probably on sandy beaches; in fact, while but one species is known 

 to live part of its time, at least, in the gills of other fishes there are a 

 number of species that have only been caught in the open. Several years 

 ago Prof. J. D. Anisits, then living in Asuncion, Parag-uay, sent me one 

 of these little creatures, which he had caught in a brook near Sapucay. 

 He tried to get others but sorrowfully reported that the locality was 

 gone, the arroyo was dry. While the original member of the Stego- 

 philini came from a medium altitude, the members of the subfamily live 

 largely in the lower levels of the Amazon and La Plata. As it is more 

 probable that specimens living in the open will get into the ichthyologists' 

 bottles than those living in the gill-cavities of larger fishes, it must be 

 left an open question whether the species living in gill-cavities are more 

 numerous than those living in the open, and whether the same species 

 live in the open and in gill-cavities indiscriminately, or whether they 

 only occasionally get into gill-cavities as the result of their inborn, in- 

 sinuating habit coupled with the blood-sucking specialization. 



The three known species of the Tridentinse, all collected during the 

 Thayer Expedition, in the Amazon Basin near the boundary between 

 Brazil and Peru, were described by my wife and myself in 1898. One of 

 them, Miuroglanis platycepiialus, captured in 1866 by the combined 

 efforts of James, Thayer and Talisman, in the Jutahy, is or was only 

 seventeen millimeters long. A recent effort to locate the specimen has 

 failed. The same fate seems to have befallen the specimen of Tridens 

 brevis. It was but twenty-one millimeters long, and caught in 1866 by 

 Bourget at Tabatinga. The third and last of this group is Tridens 

 melanops. In 1866 the future philosopher, William James, caught twen- 

 ty-seven of them at Iga, the largest only twenty-seven millimeters long. 

 In 1891 the Museum of Comparative Zoology sent me one of these, which 

 has just been figured for my monograph. The Tridentinse are fishes 

 with a greatly depressed head and a large eye placed on the edge of the 

 head; in one, at least, they look down rather than up. 



One of the Vandelliini, Branchioica bertcni, lives in the gill-cavities 



