306 CALIFORNIA ACADEMY OF SCIENCES. 



Dr. Bleeker examined a specimen in the Leyden Mu- 

 seum from Surinam, which he said was the species fig- 

 ured by Bloch. He also says that it is a true Ageneiosus, 

 and the assumption of Dr. Steindachner, that Bloch 

 overlooked the mental barbels in his dried (?) specimen, 

 seems unwaranted. 



The species is marked by its long lower jaw and by the 

 long dorsal spine, which is provided with two groups of 

 hooks on its outer margin. 



240, Ageneiosus caucanus. 



Ageneiosus caucamis Steiudachuer, Fisch-fauna des Cauca & Fliisse 

 bei Guayaquil, 9, pi. vi, fig. 1-1, 1879 (Cauca). 



This species is known to us only from the description 

 and plate by Dr. Steindachner. 



241, Ageneiosus ucayalensis. 



Ageneiosus ucayalensis Castelnau, Aiiini, Am. Sud. 49, pi. xvii, fig 2, 

 1855 (Ucayale); Eigenm. & Eigenm. Proc. Cal. Acad. 2d Ser. i, 

 150, 1888 (Para). 



Habitat: Amazon at Para; Ucayale. 



As the types of this species are said to have come from 

 the Ucayale river, our specimens may be distinct from it. 



Body elongate, about as high as wide in front of the 

 ventrals, becoming strongly compressed behind the ven- 

 tral fins. Head covered with skin, much depressed, the 

 snout pointed, spatulate; the surface of the bones with 

 longitudinal ridges. Fontanel continued backward as a 

 groove to near the occipital process. Occipital process 

 as broad as long, firmly joined to the dorsal plate. Width 

 of the head little less than 2 in its length; width of the 

 rictus scarcely less than the greatest width. 



Eye lateral, 3J-4 in snout, 7-i-S in head, 3-i- in the iii- 

 terocular. 



Maxillary barbels simple, not reaching to the angle of 



