NOTROPIS 131 



h. Maxillary reaching' posterior nostril; mouth moderately oblique, making 40 

 to 60 with vertical; teeth 0, or 1, or 2, 4-4, 0, or 1, or 2; peritoneum 

 silvery heterodon. 



hh. Mouth extremely small and upturned, the maxillary scarcely reaching 

 anterior nostril, and making an angle of 20 to 30 with vertical when 

 mouth is closed; teeth 4-4; peritoneum black anogenus. 



ff. Black lateral stripe, if present, developed only posteriorly (not continued 

 forward through eye to end of snout). 



i. Mouth more or less oblique, jaws subequal; lateral line distinctly decurved 

 anteriorly. A dark vertebral streak, and a plumbeous lateral band more 

 or less distinct posteriorly; scales of lateral line of average depth; length 

 2y 2 inches blennius. 



ii. Mouth little, if any, oblique, tip of upper lip below level of lower margin of 

 orbit; lower jaw distinctly shorter than upper; lateral line nearly straight. 



phenacobius. 



ee. Scales before dorsal smaller, 17 to 19 in number; mouth inferior, lips rather 

 thick; teeth 1, 4-4, 1 gilbert!. 



dd. Eye very large, 2% to 2% in head; dark lateral stripe not developed an- 

 teriorly; some dusky color on chin at tip; teeth 1, 4-4, 1; length 3 inches. . 

 illecebrosus. 



cc. Large species, 4 to 6 inches in length when adult; plumbeous lateral stripe 

 not continued to head; course of lateral line not anywhere marked out by 

 conspicuous dark spots above and below each pore; a broad vertebral 

 streak always present; teeth 1 or 2, 4-4, 1 or 2. 



j. A prominent black spot at base of caudal fin; scales before dorsal 18 to 20. 



hudsonius. 



jj. No black spot at base of caudal; scales before dorsal 15 or 16 ....... . jejunus. 



bb. Eye small, 4 to 5 in head in adults; body more or less distinctly compressed, 

 the back sharply rounded in front of dorsal fin; scales closely imbricated; 

 teeth 4-4 or 1, 4-4, 1. 



k. Body very short and deep, the depth 3 to 3.3 in length; usually no dark 

 color on posterior membranes of dorsal fin, teeth as a rule 4-4, sometimes 

 1, 4-4, 1 or lutrensis. 



kk. Body more elongate, depth 3% to 4 in adults; a more or less distinct black 

 blotch on last membranes of dorsal; teeth 1, 4-4. 1 whipplii. 



aa. Anal rays 9, 10, 11, or 12; teeth 2, 4-4, 2. 



I. Dorsal fin in front of or over ventrals; exposed portions of scales of flanks 

 notably deeper than long; a broad dark - vertebral streak; anal rays 9 or 

 10, usually 10 cornutus. 



II. Dorsal fin behind ventrals; scales roundish, the exposed portions not notably 

 deeper than long. 



m. Scales loosely imbricated, those before dorsal in 15 to 17 series; no black 

 spot at base of dorsal. 



n. A dark vertebral streak; anal rays 9 or 10 pilsbryi. 



nn. Vertebral streak very narrow and usually faint. 

 o. Eye equal to or longer than snout; maxillary equal to eye; snout blunt; 



anal rays 9, 10, or 11 (usually 10) atherinoides. 



oo. Eye shorter than snout; maxillary 1% times eye; snout sharp; anal rays 



9 or 10 rubrif rons. 



mm. Scales closely imbricated, about 30 series in front of dorsal; a black spot 



usually evident at front of base of dorsal; anal rays 10 to 12, usually 



umbratilis. 



