SOUTH AMERICAN NEMATOGNATHI. 283 



Aiichenipterichthys ihoracaius Bleeker, Nederl. Tijdschr. Dierkunde, 

 i, 89, 1863 (uame only); Eigeum. & Eigenm. Proc. Cal. Acad. 2d 

 Ser, i, 154, 1888 (Coary; Hyavary). 



Atichenipterus thorackus Giiuther, Cat. Fish. Brit. Mus. v, 194, 1864 

 (copied). 



Habitat: Solimoeus and its tribi;taries. 



Body short and rather robust; depth greatest below the 

 dorsal spine, everywhere greater than the width. Head 

 short and broad; its greatest depth 1| in its length, its 

 greatest width about equal to its length; width at the ric- 

 tus li-lj in its length. Snout broad and rounded in 

 front, depressed. Fontanel open in front. Dorsal plate 

 twice as wide at the narrowest part as its length on a 

 median line, with a descending process behind, the sur- 

 face of the dorsal plate granular. Scapular process al- 

 most meeting the humeral process. Coracoid process ex- 

 posed, granular, forming a plate on the sides of the abdo- 

 men. 



Eye with a bony orbit, its diameter twice as long as 

 the snout, 3 in head, 2 in interorbital. 



Mouth narrow, inferior, its width 2-2} in the head; 

 teeth all villiform, the intermaxillary band somewhat 

 shallower in the middle. 



Maxillary barbel reaching to base of pectoral; mental 

 barbels shorter than the eye, postmental little longer 

 than the eye, the barbels longer in small examples. 



Gill-opening reaching base of pectoral. Humeral pro- 

 cess long and pointed, reaching beyond the middle of 

 the pectoral spine, its surface more granular than the 

 bones of the head. Pectoral pore small. 



Distance of dorsal spine from the snout 2| in the 

 length; dorsal spine in the 5 sometimes reaching the adi- 

 pose fin, 23-33 in the length, in the ? much shorter, 

 3|-4 in the length, its outer margin slightly roughened, 

 its inner margin with wide-set teeth. Distance between 

 the dorsal and adipose fins 21-21 in the length. 



