Jordan and Evennann . — Fishes of North America. 1313 



of snout to caudal peduncle ; ventral outline curved from chin to breast, 

 thence straight to anal spine, and slanting obliquely upward to caudal 

 peduncle. Snout small and pointed; mouth small and oblique, the lower 

 jaw slightly projecting; teeth all small, the outer scarcely enlarged; pre- 

 opercle finely serrate, the posterior limb somewhat concave, the angle 

 broadly rounded. Gill rakers short and slender, about i the diameter of 

 pupil, 8 + 15; scales above lateral line arranged in oblique series; tip of 

 snout, chin, and maxillary naked; scales on head small and crowded; soft 

 fins scaled. Pectoral reaching to vent; ventrals reaching halfway to 

 second anal ray ; second anal spine a little longer and stronger than third ; 

 upper lobe of caudal the longer, about equal to head. Color as in Lythrii- 

 lon JJaviguttatum, in spirits, dark steel gray; a small very distinct pale 

 8i)ot on each scale of back and sides, surrounded by darker, this spot, in 

 spirits, light yellowish; in life of a pearly blue; head plain; a small 

 dusky blotch under angle of preopercle; fins plain bright yellow in life. 

 Young with a large black blotch at base of caudal, as in Jlwmulon stein- 

 dachneri and Orthostcechus macuUcauda, and without the dusky horizon- 

 tal streaks seen in most of the other species. This species differs from 

 L. flai'iguttahim in having fewer gill rakers, the depth and arch of the 

 back greater. Rather common in the estuary at Mazatlan, not yet noticed 

 elsewhere; all the specimens of Lytlirulon from other localities examined 

 I)y us being referable to L. flangnttatum. Described from a specimen 

 9 inches long from Mazatlan. The species is probably not rare, but has 

 been confounded with the preceding, {opalenccns, opal-like, referring to 

 the pearly spots.) 



Lythrulon opalescens, Jordan & Staeks, Fishes of Sinaloa, in Proc. Cal. Ac. Sci. 1895, 

 459, pi. 40, Mazatlan (Typo, No. 290,'!, L. S. Jr. Univ. Mus. Coll. Hopkins Expert, to 

 Sinaloa). 



541. ORTHOSTCECHUS, Gill. 



(Sti;ii'ei> Ghunts.) 



Orthostcechus, Gill, Proc. Ac. N,at. Sci. Phila. 1862, 2.'):) (macuUcauda). 



This genus is closely allied to Ilamulon, differing most obviously in the 

 arrangement of the large scales, which are throughout in series parallel 

 with the lateral line; the fins are long and low, the gill rakers rather 

 numerous, the chin projecting; the skull not essentially different from that 

 o{ H(vviulon. One species. (o/aOo?, straight; (Jro?^o?, row.) 



1G80. ORTHOSTCECHUS MACULICAUDA, Gill. 



(RONCADOK IvAIADO. ) 



Head 3^ ; depth 25 ; eye large, 3| in head in adult. D. XIII (rarely XIV), 

 15; A. Ill, 10; scales 5i-51-ll. Body oblong-elliptical, not much com- 

 pressed; the back little elevated. Head rather large, moderately pointed 

 anteriorly; the profile nearly straight from the snout to the nape; snout 

 short, low, rather pointed, its length 3i in head; mouth small, a little 

 oblique, the maxillary extending to front of pui)il, its length 2J in head; 



