SOUTH AMERICAN NEMATOGNATHI. 41 



43. Hisonotus notatus sp. nov. 



? Otocinclus macuUcauda Steiudachuer, in part. 



Types, No. 7764; iiiuety-five specimen^-, the largest .04 m. long. Santa 



Cruz. Dom Pedro II. 

 No. 8177; one s;)ecimen .0i3 ni. Juiz de Fora. Thayer expedition. 



Body somewhat depressed anteriorly, wider tlian deep. 

 Head narrow and comparatively liigli; occipital ending in 

 a triangular process which is bordered by a single nuchal 

 plate; profile rather steep and slightly convex; all the plates 

 of the head strongly hispid; a series of rather large re- 

 curved spines margining the granular portion of the snout 

 below. Orbit 3J in the snout, 7 in the head, 3 in the inter- 

 orbital. 



Ventral surface with about 3 series of irregular plates. 

 Lateral plates strongly hispid, the marginal spines scarcely 

 enlarged. 



Distance of dorsal fin from tip of snout little more than 2 

 in the length; margin of dorsal fin convex. Caudal emar- 

 ginate. 



Pectoral spine not reaching middle of ventrals, its outer 

 margin spiny. 



Light brown; caudal with a large median blackish spot 

 which extends to the tip of the middle caudal rays, outer 

 caudal rays yellow. 



Head 3; D. I, 7; A. I, 5; Y. I, 5; P. I, 6: kit. 1. 25. 



Parot(>cmclus subgen. nov. 

 Adipose fin present. 



44. Hisonotus maculicauda (Steindachner). 



Locality: Santa Cruz. 



VIII. Otocinclus Cope. 



45. Otocinclus affinis Steindachner. 



Locality: Santa Cruz, 



46. Otocinclus vestitus Cope. 



