204 MEMOIRS OF THE CARNEGIE MUSEUM 



Sides everywhere lightly peppered with cliromatophores; an hour-glass-shaped 

 dark bar across the base of the caudal. 



Ageneiosus Lacepede. 

 Ageneiosus Lacepede, Hist. Nat. Poiss., V, 1805, 132 {armatus); IX, 167 

 Pseudageneiosus Bleeker, Nederl. Tijdschr. Dierk., I, 1863, 108 {davalla). 

 Ageniosus GtJNTHER, Catalogue, V, 1864, 191 (sp.). 



Type, Ageneiosus armatus Lacepede. 



Maxillary barbels only; air-bladder minute, concealed under the peritoneum 

 and largely covered with bone; no pseudo-tympanum. Snout much longer than 



the eye. ^^^ ^^ ^^^ Guiana Species of Ageneiosus. 



a. Caudal deeply forked. . j tv,,. Vopth larB-p- 



b 1 45; back with obscure marblings; maxillary band of teeth comma-shaped, the teeth larg , 



■ ■ dorsal and pectoral spines slender, pungent; origin of anal a little nearer base of naiddle 



caudal ravs than the rictus; pectorals not reaching ventrals. Head 4; 1. 1,14, ci. «• 



guianensis. 



aa. Caudal emargmate; dorsal and pectoral rays smooth on posterior margin, the pectoral ray not 



. Do^'^me strong, sinuate, rough or spinous in front; profile steep, concave, ori^n c^ juial 

 equidistant from base of middle caudal rays and anterior margin of eye; pectoral falcate 

 the first ray reaching beyond origin of ventrals; head 3.66; P. 1,14; Br. 9; A- J^^^^^k 

 above, lighter below 



cc First dorsal ray not spinous; profUe nearly straight and horizontal; origin of anal a httle nearer 

 origin of pectoral than to base of middle caudal rays; pectoral rounded, not reachmg ven- 

 trils- head .3 33- P. 16; Br. 10; A. 29. Conspicuously marked with hght and dark. 



' marmoratus. 



75. Ageneiosus guianensis sp. nov. (Plate XXI, fig. 2.) 



Type unique, a female, 175 mm. Wismar. (Carnegie Museum Catalog of 



Fishes No. 1712a.) . , „ 



Head 4; depth 5.5; D. 1,6; A. 45; V. 8; P. 1,14; Br. 9; eye 3 m snout, 6 



in head, 3.5 in space between the eyes below. 



Profile concave, not very steep, snout much depressed; width of head 1.4 in 

 its length ; length of snout less than interocular width by about an orbital diameter ; 

 fontanel reaching above middle of eyes, the groove considerably farther; cleft ot 

 mouth 3 in the length of the head ; half the maxillary barbel osseous, its tip i-eachmg 

 rictus; premaxillary band of teeth comma-shaped, widest in front, its width halt 

 the length of the "eye, the teeth comparatively large. Gill-openings extending 

 to below the posterior margin of the eye, the space between them about equal to 

 the diameter of the eye. 



