THE AMERICAN TETRAGONOPTERINAE. 



237 



Specimens examined. 



Head about 4; depth about 2.5 ; D. 11; A. 33-40; scales 8^1 to 48-7 or 8 ; 

 eye 2.75-3 in the head, equal to the interorbital in the largest; less than inter- 

 orbital in the smaller. 



Compressed, subrhomboidal, elongate; head bluntly subconical. Pre- 

 ventral area narrowly rounded, the median series of scales not quite regular; 

 postventral area narrowly keeled. Predorsal area bluntly keeled; the median 

 line largely naked in the adult, about 17-20 scales between the dorsal and occi- 

 pital process along one side of the median line. 



Occipital process about one fifth of the distance from its base to the dorsal, 

 bordered by about 5 scales; profile slightly depressed. Interorbital rovmded. 

 Frontal fontanel two thirds the length of the parietal without the occipital groove. 

 Second suborbital leaving one foiu-th or less than one fourth the width of the 

 cheeks naked. Mouth very small. MaxiUary not much more than half the 

 length of the eye, nearly vertical, not reaching the eye. Mandible equals the 

 eye in length ; three to five teeth in the outer row of the premaxillary, four very 

 broad teeth in the inner row, their denticles arranged in distinct crescents. No 

 maxillary teeth. Dentary with four larger graduate teeth (those of the two 

 dentaries arranged in a distinct crescent) and one or two smaller ones scarcely 

 evident; no teeth in side of lower jaw, the dentiferous ridge raised, scale-like 

 at its end. 



Gill-rakers 10 + 12, about equal to posterior nostril. 



Dorsal a little nearer caudal than tip of snout, obliquely truncate, its 

 longest ray 4 in the length. Origin of anal under middle of dorsal, its border 

 but little emarginate. Ventrals scarcely reaching anal, their origin under the 



' Largest specimen. 



^ Leland Stanford Jr. University Collection. 



