40 CALIFORNIA ACADEMY OF SCIENCES. 



series of plates lias a median keel which is strongest above 

 tip of anaL 



Distance of dorsal lin from tip of snout about 2f in the 

 length; first dorsal ray as high as tlie space between base 

 of pectoral and tip of snout. Caudal fin broken. 



Anal fin as high as length of snout plus the eye. Vent- 

 rals short, not reaching the anal. Pectorals extending be- 

 yond middle of ventrals, little lower than the first dorsal 

 ray; the spine strongly spiny on its outer margin, almost 

 smooth on its inner margin. 



Back marbled; sides with numerous minute dark dots; 

 dorsal rays spotted with dark; middle caudal rajs blackish; 

 anal, and inner surfaces of ventrals and pectorals spotted 

 like the dorsal fin. 



D. I, 7; A. 0; V. I, 5; P. 1, 5; lat. 1. 20. 



We have dedicated this species to Professor R. Ramsey 

 Wright of Toronto, who has contributed more than any one 

 else to the knowledge of the anaiomy of the American Nem- 

 atognathi. 



YI. Hypoptopoma Giinther. 



40. Hypoptopoma thoracatum Giinther. 



H. hilohatum Cope. Otocinclus joherti Vaillaut. 



Localities: Teffe; Obidos; Mauacapmu; I(^a; ? Rio Negro. 



41. Hypoptopoma gulare Cope. 



42. Hypoptopoma carinatum Steindacbner. 



VII. HisoNOTUS gen. nov. 



Type, Hisonoiiis notatus, sp. uov. 



Belly with large plates; eyes superior; humeral plate im- 

 perforate. 



§ Hisonotus. 



Adipose fin none. 



