204 BULLETIN 189, UNITED STATES NATIONAL MUSEUM 



cc. Body excessively deep, ovate, extremely compressed; forehead very steep 



to nearly vertical, its outline forming an obtuse angle with that of back; 



depth usually greater than half length. 



j. Anterior profile nearlj' vertical, more or less concave; chord of arch in 



lateral hne shorter than straight part, posteriorly with small bony 



scutes; second dorsal and anal never with high lobes anteriorly. 



Vomer (p. 222) 



jj. Anterior profile never vertical, scarcely if at all concave; chord of arch 



in lateral line equal to or longer than straight part, without bony 



scutes; second dorsal and anal with high lobes anteriorly in adults. 



Selene (p. 223) 

 Genus DECAPTERUS Bleeker, 1851 



Body rather elongate, little compressed; head rather short, moder- 

 ately pointed; mouth fairly small, nearly or quite terminal; premax- 

 illaries protractile; maxillary broad, with a supplemental bone; 

 straight part of lateral line, posteriorly, armed with bony scutes; 

 second dorsal and anal each with a well-detached finlet; pectoral short. 



A single species is known from Peru. 



DECAPTERUS AFUERAE. new species 



JUREL FIND 



Decapterus scombrinus Evermann and Radcliffe (not of Cuvier and Valen- 

 ciennes), 1917, p. 58, Lobos de Afuera, Peru (description; relationship 

 discussed). 



7 Decapterus sanctae-helenae Walford (not of Cuvier and Valenciennes), 1937, 

 p. 82, pi. 7, fig. C. 



Head 3.75; depth 4.7; D. VIII-I, 32-1; A. II-I, 27-1; P. 20 or 21. 



Body rather robust, its greatest thickness about two-thirds the 

 depth; back little elevated; caudal peduncle depressed, its depth 7.8 

 in head; head low; snout somewhat pointed, 3.35 in head; eye 4.25; 

 interorbital 4.1; mouth oblique; lower jaw projecting somewhat; 

 maxillary broad, with a concave posterior margin, scarcely reaching 

 anterior margin of eye, 3.1 in head; teeth in upper jaw obsolete, 

 a series of small teeth in lower jaw, vomerine patch with a long 

 backward extension, palatine bands very narrow; shoulder girdle with 

 a pronounced notch and a prominent projection above it midway 

 between pectoral and ventral; gill rakers slender, about two-thirds 

 length of eye, 33 on lower and 10 on upper limb of first arch and with 

 17 spiny knobs on its inner side; lateral line with a long, low curve 

 anteriorly, becoming straight approximately over origin of anal, the 

 chord of the curved part much longer than the straight part, provided 

 with modified scales throughout, becoming hard and bony (scutes) 

 posteriorly, 73 scales, followed by 32 scutes, each 35 with a rather 

 definite spine; scales missing on top of head anterior to postorbital 

 margins, and on snout, with a narrow strip of 3 or 4 rows of scales on 

 cheek; spines of first dorsal slender, the fourth the longest, failing to 



