SOUTH AMERICAN NEMATOGNATHI. 259 



very steep from the dorsal spine to the eye, thence much 

 steeper forward, the space in front of the anterior nos- 

 tril somewhat concave. Bones of the head finely granu- 

 lar, the sutures showing as smooth grooves; an ovate 

 foramen covered with skin between the dorsal plate, occi- 

 pital process and a plate of dermal ossification. 



Scapula with a distinct dermal ossification, which, at 

 its narrowest part is as wide as the foramen, not meeting 

 the humeral process, its surface finely granular. Fon- 

 tanel narrow and short, not as long as the eye, its 

 center over the pupil; a bridge across its posterior fifth. 

 Dorsal plate reenforced on the sides by dermal ossifica- 

 tions, their divisions marked by a smooth line. 



Eye large, placed high and far back, midway between 

 posterior margin of the dorsal plate and the tip of the 

 snout, measuring, to the orbital rim, 1J 2 in snout, 

 3-3f in head, the interorbital width J-J less than the 

 orbital diameter. 



Maxillary barbels reaching the gill-opening, except in 

 the old; all the barbels united by a membrane, the men- 

 tal barbels continuing as a thickening of the membrane, 

 a branch of the thickened membrane of the postmentals 

 extending to the margin of the membrane giving the 

 appearance of an extra outer pair of barbels; the men- 

 tal barbels short, their bases thickened and covered with 

 short, fleshy cirri. 



Snout covered with skin; posterior nares about equi- 

 distant between the anterior nares and the eye, the an- 

 terior nares about equidistant between the eye and the 

 tip of the snout; mouth very small, wholly inferior; a 

 very small patch of villiform teeth on each intermaxil- 

 lary, a larger patch on each dentary bone. 



Gill-openings rather wide, the isthmus about equaling 

 the orbital diameter. Coracoid bones covered with skin, 

 but externally evident as a ridge. 



