THE AMERICAN TETRAGONOPTERINAE. 243 



Head 3.8; depth 3; scales 8 or 9-42 to 47-5 or 6 ; D. 11; A. 27-30; eye 2.56 

 in head; interorbital about equal to the eye. 



Compressed, elongate, regularly elliptical to the base of the caudal peduncle. 

 Preventral area rounded or flattish, without a median series of scales; post- 

 ventral area keeled. Predorsal Une feebly keeled, naked in front, some of the 

 scales near the dorsal with their edges bent over the back and sometimes a median 

 scale. 



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

 bordered on the side by about 4 scales. Interorbital about equal to the eye, 

 convex. Frontal fontanel not much shorter than the parietal, exclusive of the 

 groove on the occipital process. Second interorbital bearing a naked area which 

 is widest below. Premaxillary with four teeth in the front series, the second 

 tooth removed from the hne of the rest ; second row with five teeth, their den- 

 ticles arranged in a curved line. Maxillary with two minute teeth; lower jaw 

 with four large teeth and a number of abruptly smaller ones of which the first 

 three may be 3-pointed. 



Gill-rakers about 8 + 15, i the diameter of the eye. 



Scales cycloid, regularly imbricate, the rows not deflected to the anal and 

 no auxiliary rows; each scale with several (2-11, usually 6-10) scarcely diverg- 

 ing striae. Caudal naked. Anal with a feeble sheath of a single row of cadu- 

 cous scales. Lateral line forming a downward curve to above the anal, the 

 row of scales below it parallel with it for its entire length; axillary scale small. 



Origin of dorsal a little in advance of middle of body, pointed, the next to 

 the last ray nearly half as long as the highest, which is 3| in the length. Caudal 

 lobes slightly longer than the longest dorsal ray, the lower lobe a Uttle the longer. 

 Anal emarginate, the 10th ray about half as long as the longest; origin of anal 

 and base of last dorsal ray equidistant from tip of snout. Ventrals scarcely 

 reaching anal, their origin and the 3d scale in front of the dorsal equidistant from 

 tip of snout. Pectorals reaching ventrals. 



A faint, vertical himieral spot, a sptu of it crossing the third scale of the 

 lateral line; end of caudal peduncle whitish, a broad, dark bar crossing the base 

 of the caudal, blackest in the center where it is continued to the end or to near 

 the end of the middle rays. A narrow, silvery, lateral band. 



Vertebrae 13 + 19. 



Anterior air-bladder two thirds as long as the posterior; the posterior 

 sausage-shaped, but little decvu-ved behind and ending bluntly. 



Alimentary canal not quite equal to the entire length. 



