EIGENMANN : FRESH WATER FISHES. 243 



Ariiis vUlosiis Philippi, 1. c, 712 (Santiago). 

 Arius squalus Philippi, 1. c, 713 (Santiago). 

 Arius micropterus Philippi, 1. c, 713 (Santiago). 

 Arius synodon Philippi, 1. c, 713 (Santiago). 



Habitat: Central portion of Chili. 



The numerous species of Philippi seem to be based on individual differ- 

 ences. The seventh dorsal ray is always divided to near its base, and in 

 one of the specimens examined by me there are eight dorsal rays. 



Slender, terete forward, compressed toward the tail ; the width, below 

 the dorsal spine, equals the depth. Head short and blunt, somewhat 

 pointed in young, the profile strongly decurved in front; head entirely 

 covered with a layer of muscle and skin, the surface of the bones irregular, 

 rugose, the interorbital portion flattish, postorbital portion with two nearly 

 parallel median ridges, fontanel between the two median ridges, extend- 

 ing from the occipital process to in front of the eyes, with a broad bridge 

 behind the eyes. Occipital process a deep but short crest. 



Eye small, circular, 3 in snout, little more than i in the interorbital, 3 

 in the interocular, 7^ in the head. 



Nostrils close together, with a membrane around the entire margin 

 forming an 8-shaped figure, the portion of the membrane separating the 

 nasal openings highest. 



Maxillary barbel broad and flattened at its base, scarcely reaching the 

 base of the pectoral. 



Snout sometimes long and pointed, usually rounded, projecting con- 

 siderably beyond the lower jaw. Lips thick and strongly papillose. 

 Maxillary bones reaching to below the eye, 2f in the head. The anter- 

 ior half of the maxillary consists of a slender peduncle bearing two series 

 of teeth ; the posterior portion is flattened and about three times as wide 

 as the anterior portion. Premaxillaries with a crescent-shaped patch of 

 teeth, the outer four or five series compressed, incisor-like ; teeth of the 

 inner series very much smaller, not incisor-like. Vomer with two oval 

 patches of large conical teeth, the patches becoming united with age. 

 Teeth of the lower jaw compressed, incisor-like ; the band deep in front 

 tapering rapidly to the rictus. 



Gill-membranes usually separate to below the eye, entirely free from 

 the isthmus. Gill-rakers 5 + 8. Pseudobranchiae well developed, not 

 covered by a membrane. 



