SOUTH AMERICAN NEMATOGNATHI. 273 



and marblings; ventral surface bright yellow dotted with violet. Head 

 4; depth about 4; D. I, 5; A. 23; V. 7-8; P. I, 7. (Steindachner.) 



f/laber 212. 

 ad. Head granular above. 



b. Caudal emarginate. 



c. Fontanel open in front. 



d. Maxillary bone short; dorsal spine straight or only slightly 

 curved. 



e. Dorsal spine as long as the pectoral spine. V. 7; D. I, 5; A. 

 22; dorsal spine finely serrate on both edges, pectoral spine 

 more coarsely; mandible a little projecting. Eye obscure. 

 Maxillary barbels reaching end of pectoral spine; mental bar- 

 bels about equal to orbital diameter. Humeral process reach- 

 ing beyond middle of pectoral spine, coarsely striate, the striae 

 nodular. Head finely rugose above, not covered with skin. 

 Lead color; dorsal fin with a black spot above. Head rather 

 wide, 4 in the length. (Cope.) isacanthus 213. 



dd. Maxillary bone extending to posterior margin of the eye or 

 much longer; dorsal spine curved forward with two groups of 

 spines on its anterior margin. Maxillary barbel reaching to the 

 tip of the pectoral. Lower jaw somewhat projecting; eye 4|-5i 

 in the head. Fontanel open in front. Humeral process extend- 

 ing a little beyond the middle of the pectoral spine; posterior 

 edge of the dorsal smooth. Yellowish brown, more or less flecked 

 and dotted with darker brown. Head 4f-4; depth 4-4; D. I, 6; 

 A. 26; P. I, 7; V. 6. (Steindachner.) insignis 214. 



cc. Fontanel closed in front. 



/. Anal 19-20; D. I, 5; V. 9. Head rather coarsely granulated above; 

 lower jaw a little projecting. Maxillary and postmental barbels 

 extending to or beyond tip of humeral process; mental barbels 

 twice or thrice as long as the eye. Humeral process extends be- 

 yond middle of pectoral spine. Dorsal spine serrated along its 

 outer margin; pectoral spine along both edges; dorsal spine con- 

 siderably shorter than the pectoral spine which is as long as the 

 head. Head 4 in the length. Lat. 1. irregularly undulated. Uni- 

 form brownish black. (Giinther.) obscurus 215. 

 ff. Anal 27-30; D. I, 6. Profile straight; fontanel elongate, usually 

 open in front. Pectoral spine with strong hooks on both edges, 

 dorsal spine rough on its anterior, smooth on its posterior mar- 

 gin. Humeral process extending beyond middle of pectoral 

 spine. Maxillary barbel little longer or shorter than the head. 

 Lower jaw projecting. Eye 3f-4 in the head. Back dark violet 

 with innumerable darker dots, lower parts lighter, middle of 

 caudal with a dark bar. Head 4-4|; V. 6; P. I, 6. (Steindachner.) 



maydalencK 216. 

 bb. Caudal obliquely truncate or rounded; lower jaw longer. 



18 



