256 CALIFORNIA ACADEMY OF SCIENCES. 



Hemidoras stenopeltix Eigenm. & Eigeiim. Proc. Cal. Acad. 2d Ser. 



i, 158, 1888 (Kio Negro; Manaos; Hyavary; Manacapuru; Teff<'; 



Tabatinga; Obidos). 

 Habitat: Amazon, Solimoeiis. 



Elongate, slender, little compressed. Head long, 

 slender, pointed; interorbital area flattish, occipital re- 

 gion convex in transverse profile; opercle, suborbital and 

 bones of the crown granular. Fontanel a simple opening, 

 somewhat shorter than the eye, continued forward as a 

 broad groove, and backward as a groove to the tip of the 

 dorsal plate; two small, oval foramina on either side of 

 the suture between the occipital process and dorsal plate. 

 Dorsal plate much broader than the interorbital width. 



Eye 1^-2 in snout, 3|-4| in the head, |-1 in the inter- 

 orbital; snout long and pointed; width at the rictus about 

 equal to the eye; intermaxillaries and dentaries each 

 with a small patch of villiform teeth. 



Maxillary barbel extending beyond base of pectoral 

 spine, with a series of about 16 short filaments on its 

 outer margin; mental barbels short, with very short fila- 

 ments, all the barbels connected by membranes.' 



Gill-openings extending forward to below eyes. 



Two or three large flat plates in front of a lateral scute 

 which connects the humeral process and dorsal plate; 

 the lateral scutes following are very narrow and high 

 and obliquely placed, the highest one 2 in the head; 

 each scute with a series of fine marginal spines above 

 and below the median hook; a series of flat plates be- 

 tween the dorsal and adipose fins and between the vent 

 and the anal fin. In the young the plates are less de- 

 veloped and more or less concealed. 



Humeral process extending to below the dorsal spine 

 or second dorsal ray. Pectoral pore simple, large. 



Distance of the dorsal spine from the snout 2J-2| in 

 the length; dorsal spine slightly curved, little higher 

 than the length of the head, its sides grooved, the lower 



