THE AMERICAN TETRAGONOPTERINAE. 235 



Allied to A. alleni, much slenderer and the scales of the lower sides regularly 

 imbricate except over the muscles of the anal. 



Head 4.25; depth 2.5 in 10,245 (female); 2f in 10,246 (male); D. 11; A. 

 41-45; scales 9 to 11-45 to 50-8; eye 2.5-2.75, interorbital equals eye. 



Elongate compressed, the dorsal and ventral profiles equally arched in 

 the male, without humps or depressions; in the female the ventral profile is 

 deeper than the dorsal, and regular, the dorsal profile somewhat humped at the 

 occiput. Preventral area narrowly rounded, without a regular median series 

 of scales; postventral area narrowly compressed. Predorsal area keeled, naked 

 except just in front of the dorsal where the scales of one side sometimes have a 

 narrow margin bent over the back; about six scales bordering the occipital 

 process on the side. 



Occipital process 3 to 4 in the distance from its base to the dorsal, being 

 longer in the deep specimens ; occipital fontanel nearly twice as long as the frontal 

 and continued as a groove to the tip of the occipital process. Interorbital con- 

 vex. Second suborbital, as in A. alleni, leaving a narrow naked area around its 

 free margin. Mouth small, anterior margin of maxillary much arched, its upper 

 part vertical, equal to the snout or shorter, 4.2^.5 in the head. Mandible 2.75 

 in head. Five teeth in the outer series of the premaxillary, the third removed 

 from the line; five teeth in the inner series, the points of the middle ones, at 

 least arranged in a U-shaped series. Fom- graduated asymmetrical teeth and a 

 number of small ones on the dentary. Maxillary with a single tooth. 



Gill-rakers 10-1-16, longest equal to about one third the diameter of the eye. 



Scales very feebly cihate, rather irregularly imbricate, there being small 

 and large scales, rows regular without interpolated series except over the anal 

 musculatm'e. Lateral line but little deciuved, the row of scales below it parallel 

 with it; a variable axiUary scale. Caudal naked. Anal with a low sheath of 

 two or three series of scales. 



Origin of dorsal usually a little nearer snout than base of caudal; dorsal 

 pointed, its height 3-3.33, in the length. Origin of anal and base of middle 

 dorsal ray equidistant from tip of snout; anterior anal rays higher but the 

 margin nearly straight. Ventrals reaching anal. Pectorals considerably be- 

 yond origin of ventrals; origin of ventrals and 7th scale in front of the dorsal 

 about equidistant from tip of snout. 



A silvery, lateral band, narrowed on the caudal peduncle and interrupted 

 in front by a vertical humeral spot ; humeral spot bordered in front and behind 

 by a pigmentless area, that behind bordered on its part by a faint second humeral 



