26 CALIFORNIA ACADEMY OF SCIENCES. 



Biplomystax Gunther, Cat. Fish. Brit. Mus., v, 180, 

 1864 (pcqnllosus). 



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 Linnfeus Syst. Nat. Ed. xiii, 1359, 1788 (Chile). 



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



(Fresh waters of Chile). 

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



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



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

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



(Chile). 

 Diplomystes papillosus Eigeum. & Eigeum. 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 see m 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 



