SOUTH AMERICAN NEMATOGNATHI. 145 



sprinkled wiih brown dots; a black median line on the 

 back; fins dusky; barbels blackish. 

 Head 85^; depth 6*; D. I, 7; A. 20. 



117. Tachisurus rugispinis (Cnv. & Val.) 



Locality: Para. 



118. Tachisurus phrygiatus (Cuv. &Val.) 



Arliis dierperinkl Bleeker. 

 Locality: Maranhao. 



119. Tachisurus grandoculis Steindachner. 

 Locality: Eio Doce. 



§ TacMsiirus. 

 120 Tachisurus nuchalis (Giinther.) 



121. Tachisurus agassizii sp. uov. 



T3'pe, No. 7670, oue specimen; lengtb .235 m. Rio Graude do Sul. 

 Seuhor Albuquerque. 



Body compressed, especially backward, the depth greater 

 than the width. Head narrowed forward, its greatest width 

 1| in its length, its greatest depth about 1^; width at the 

 mouth 2| in the length of the head. Top of head granular, 

 the granulations forming stride nearly everywhere; occipital 

 process as broad as long, with a median ridge, the margins 

 concave. Middle of the fontanel over the posterior mar- 

 gin of the pupil, continued backward as a triangular groove 

 to near base of occipital process; interorbital area with the 

 usual four smooth ridges; humeral process roughened, 

 covered with skin; sides of the head with reticulating mu- 

 cous canals. 



Eye IJ in snout, 5\ in liead, about 3 in interocular, 2 in 

 interorbital space. 



Maxillary barbels about reaching gill opening; mentals 

 extending about half way to gill opening, the post mentals 

 not much longer. 



Upper jaw projecting; teeth villiform in the jaws, sub- 

 granular or bluntly conical on the palate, small; no granu- 

 lar teeth in the inner series of the mandible; the palatine 

 patches smaller and more diverging than in spixii. 



