SOUTH AMERICAN NEMATOGNATHI. 439 



Body elongate, its depth 1J in its width. Head broad, 

 depressed, snout broadly rounded, its margin naked, its 

 upper surface covered with small plates, sides of the 

 head with a few short bristles; interorbital somewhat 

 flat. 



Eye small, 4J in the snout, 7J in the head, 1| in the 

 interorbital. 



Entire ventral surface, a small area behind temporal 

 plate and a larger space behind the pectorals naked. 

 Plates on the lower surface of the tail smooth, covered 

 with skin; basal portion of the lateral plates covered 

 with skin. A broad naked median strip behind the dor- 

 sal fin. 



Base of the dorsal fin If in its distance from the adi- 

 pose fin; a series .of six small, keeled plates before the 

 adipose spine. 



Pectoral and ventral spines thickly covered with bris- 

 tles. 



Upper surface light brown, with obscure darker mark- 

 ings, ventral surface plain; a dusky spot above the ven- 

 tral, and one above the pectoral; dorsal and ventrals 

 dusky; caudal and pectorals barred. 



HeadSJ; D. 1,7; A. 6; V. 1,5; P. I, 6; Lat. 1. 27-29. 



One specimen, .17 m. Parahyba. Thayer Expedi- 

 tion. 



XCII. ACANTHICUS. 



Acanthicus Spix, Gen. et Spec. Pise. Bras. 2, pi. 1 

 (hystrix). 



Type: Acanthicus hystrix Spix. 



This genus is most nearly related to Hemipsilichthys 

 but has no adipose fin. In the typical species the region 

 behind the dorsal is covered with rather large plates, the 

 plates in front of the dorsal are small and numerous and, 

 like those of the sides, are isolate. The entire margin 

 of the snout is beset with bristles. 



