8 TWO SPECIES OF MENHADEN. 
The yellow-fin shad feeds on microscopic organisms, but it does 
not appear to feed at the surface as does the fatback. 
The following comparison of the two species described above, based 
on specimens of like size, will aid in showing their relationship: 
BREVOORTIA TYRANNUS. 
Body, elongate, robust; depth in 
length for 10 specimens, 2.6 to 3; aver- 
age 2.85. 
Vertebra, 18+30. 
Head, long and low, its depth at mar- 
gin of preopercle less than its total 
length; head in body for 10 specimens, 
2.89 to 3.8; average 3.07. 
Radiating striations on opercle and 
preopercle strongly developed. Scales 
larger, with long, slender, finely-pointed 
serrations in adult, evident grooves on 
margin of scale between the bases of 
serrations (PI. I, fig. 1) ; rows of scales 
rather regularly placed, 47 to 54 oblique 
series along middle of side from margin 
of opercle to base of caudal; scales not 
greatly reduced on caudal peduncle. 
Caudal fin of moderate length, the 
lobes shorter than head. 
A variable number of small black 
spots on side behind humeral spot; fins 
mostly pale yellow, more or less punc- 
tulate with dusky. 
Body constantly with a dense coat of 
mucus. 
BREVOORTIA AUREUS. 
Body, deeper, less robust; sides less 
convex; depth in length for 10 speci- 
mens, 2.45 to 2.7; average 2.55. 
Vertebra, 7+39. 
Head, short and deep, its depth at 
margin of preopercle equal to its total 
length; head in body for 10 specimens, 
3.1 to 3.4; average 3.3. 
Radiating striations on opercle and 
preopercle feebly developed. Scales 
smaller, with rather short and blunt 
serrations, no evident grooves on mar- 
gin of scales between the bases of ser- 
rations (Pl. I, fig. 2); rows of scales 
very irregularly placed, 63 to 73 oblique 
series from margin of opercle to base 
of caudal; scales much reduced on 
caudal peduncle. 
Caudal fin long, the lobes longer than 
head. 
No small black spots on side behind 
humeral spot; fins all bright golden. 
Body almost wholly void of mucus. 
