SOUTH AMERICAN NEMATOGNATHI. 359 



301. Hemiodontichthys acipenserinus. 



Hemiodon acipenserinus Kner, Panzerwelse,'92, pi. vii, fig. 2, 1853 



(Eio Guaport', Matogrosso). 

 Loricaria acipenserina Gtinther, v, 260, 1864 (copied); Vaillaut, 



Bull. Soc. Philom. Ser. 7, iv, 159, 1880 (Calderon). 

 Hemiodontichthiis acipennerinus Eigenm. & Eigenm. Proc. Cal. Acad. 



2d Ser. ii, 34, 1889 (Mauacapuru; Hyavary). 

 Habitat: Eio Guapore; Solimoeus; Marafiou and tributaries. 



Greatly depressed, the depth 2 in the width. Head 

 broad, flat, its depth less than half the length of the snout; 

 occipital with 2 distinct keels which are continued on 

 the nuchal plates; dorsal plate with a median keel; three 

 plates margining the occipital; entire upper surface of 

 the head with longitudinal series of serrae; margin of 

 the head with 3 series of rather large hooks, those of the 

 lowest series strongest and longest; humeral plate with 

 radially arranged interrupted canals. Snout exceedingly 

 long and narrow^, turned slightly upward, expanded at 

 the tip, its extremity naked, the upper and lower sur- 

 faces with series of serrse, its margin near the tip with 

 several strong hooks. 



Orbit with a deep notch behind; eye Ah in the snout, 

 8 in the head, 1 in the region between the orbital 

 notches. Lower surface of the head naked. 



Teeth minute, present in the lower jaw only; lips 

 rather narrow, the lower faintly papillose. Barbels well 

 developed, their free portion about equal to the diameter 

 of the eye. 



The lateral keels stronger than in any other species of 

 Loricariince. 



All the plates in front of dorsal fin more or less cari- 

 nate. The lateral keels become approximated on the 

 12th scute. 



Region between the pectorals with 5 or more irregular 

 scutes; belly with three series of scutes; anal plate longer 

 than broad, joined to the postanal plates behind, leav- 

 ing only a narrow naked area. 



