THE AMERICAN TETRAGONOPTERINAE. 253 



a few scales with their margins bent over the back, then the median hne 

 naked. 



Occipital process between one third and one fourth of the distance from its 

 base to the dorsal, bordered by 4 scales on each side. Interorbital area broad, 

 convex. Parietal fontanel about twice as long as frontal, exclusive of the 

 groove on the occipital process. Second suborbital leaving a narrow naked area 

 around the entire free border; a distinct notch between the preorbital and the 

 first suborbital. Maxillary very obUque, 3.5-3.75 in the head, a little longer 

 than the snout. Usually four (3-5) teeth in the front row of the premaxillary 

 forming a compact series, of which the third may be somewhat withdrawn from 

 the straight line; five teeth in the second row, the denticles of the larger ones 

 arranged in a series ranging from a crescent to a U. Maxillary without teeth 

 or with one small one. Four large teeth on the dentary and numerous small 

 ones on the side. 



Gill-rakers about 10 +15, J-i the length of the eye. 



Scales cycloid, with a variable number of divergent striae, regularly 

 imbricate except on the predorsal and preventral area and sometimes over 

 the anal musculatm-e, the regular imbrication of one side joined to that of the 

 other irregularly in the preventral area; near the dorsal the uppermost row 

 of scales of the sides separated from that of the other side by a series of median 

 scales, but further forward, usually meeting irregularly and directly along the 

 middle line without median scales. Sometimes the median series of scales 

 extends forward to within a few scales of the occipital process; over the anal 

 muscles there are interpolated scales varying in number in different specimens. 

 Anal sheath consisting of two rows of scales which are free from the rays. Caudal 

 lobes without attached scales but with a basal sheath of large scales; axillary 

 scale well developed. 



Origin of dorsal a little nearer tip of snout than base of caudal, its penulti- 

 mate ray 2i in its longest ray, which is about one foiu-th of the length. Anal 

 slightly emarginate in the young, straight in the adult, the longest rays in the 

 largest specimens equal snout and eye in length, the shortest equal to snout 

 and eye to pupil. Origin of ventrals and fourth scale in front of the dorsal 

 equidistant from tip of snout; origin of ventrals equidistant from tip of snout 

 and origin of caudal in the extreme young, and last fourth of anal in the oldest. 

 Ventrals reaching anal in the youngest, faUing considerably short in the oldest. 

 Pectorals reaching slightly beyond origin of ventrals. 



A well-defined, horizontally elongate, black humeral spot on the third to 

 the sixth, or second to the fifth, scale in the series above the lateral Une and on 



