SOUTH AMERICAN NEMATOGNATHI. 43 



Greatest depth equal to the greatest width. Occipital 

 with three strong spiniferous ridges, a short median one 

 and two longer lateral ones; similar crests extending from 

 posterior margin of orbit to edge of temporal plate. Nasal 

 pits margined bj spiniferous ridges. Lower surface of 

 head naked, margined by a series of recurved spines. Cor- 

 acoid and scapula granular; belly with a small, granular 

 plate between posterior margins of ventrals; a larger plate 

 behind the pectoral. Lateral and dorsal plates keeled. 



D. I, 7; A. 6; Lat. 1. 22. 



XII. Hemiancistrus Bleeker.^ 



Pseadacanthicus Bleeker; Chcetostomns Giinther. 



We have been able to examine only two species of this 

 genus. 



54. Hemiancistrus histrix (Cuv. .t Vai.). 

 bb. Hemiancistrus serratus (Guv. & Val.). 



56. Hemiancistrus spinosus (Castelnau). 



57. Hemiancistrus medians (Kner). 



58. Hemiancistrus pictus (Kuer). 



59. Hemiancistrus brachyurus (Kner). 



60. Hemiancistrus itacua (Valen-ieuues). 



61. Hemiancistrus scaphirhynchus (Kuer). 



Localities: Hyauuary; Coaiy; Tefle; Hyavary. 



62. Hemiancistrus mystacinus (Kuer). 



63. Hemiancistrus oligospilus (Giinther). 



64. Hemiancistrus schomburgkii (Giintiier), 



65. Hemiancistrus guacharote (GuutUer). 



66. Hemiancistrus trinitates (Giiutber). 



Ana sir us guacharote Gill. 



67. Hemiancistrus aspidolepis (Giiutber). 



68. Hemiancistrus fordii (Giiutber). 



'^Should Hypostomu'i pictus Casteluau, prove to be a valid species it must 

 be reuamed. 



