26 CALIFORNIA ACADEMY OF SCIENCES. 



Diplomystax Giinther, Cat. Fish. Brit. Mus., v, 180, 

 1864 (papillosus). 



The distinctive character of this genus is the develop- 

 ment of the maxillary bone. It forms the sides of the 

 mouth and carries a very narrow band of teeth. No 

 mental barbels; maxillary barbels thick, compressed at 

 the base. Occipital process not visible externally; no 

 bony orbit. Skull with two nearly parallel median ridges 

 above. Fontanel extending to the base of the occipital 

 process, with a rather broad interruption behind the 

 eyes. 



Habitat: Chile, near Valparaiso and Santiago. 



16. Diplomystes papillosus, 



Molina "Hist. Nat. Chile, 199, No. 9." 



?? Silurus chilensis Linnaeus Syst. Nat. Ed. xiii, 1359, 1788 (Chile). 



M Pimelodus chilensis Lacepede Hist. Nat. Poiss. v, 114, 1803 



(Fresh waters of Chile). 

 Arius papillosus Cuv. & Val. Hist. Nat. Poiss. xv, 118, pi. 431, 1840 



(Valparaiso; San Jago); Gay, Hist. Chile, ii, 305, pi.: fig. 1, 



1848 (Chile); Philippi, MB. Ak. Wiss. Berlin, 1866, 710 (Chile). 

 Diplomystax papillosus Giinther, Cat. Fish. Brit. Mus. v, 180, 1864 



(Chile). 

 Diplomystes papillosus Eigenm. & Eigenm. Proc. Calif. Acad. 2d 



Ser. vol. i, 1888, 149 (Kivers of Santiago). 

 Arius carcharias " Leybold, Anales de la Universidad de Chile, 



1883 (Chile)"; Philippi, MB. Ak. Wiss. Berlin, 1866, 711 (Chile). 

 Arius villosus 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 Chile. 



The numerous species of Philippi seem to be based on 

 individual differences. The seventh dorsal ray is al- 

 ways divided to near its base, and in one of the speci- 

 mens examined by us 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 



