4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 10/ 



reviews are out of place. Therefore, this somewhat technical treatise 

 is offered as preliminary to the more general treatment given the 

 North American species in the general work mentioned. This prelimi- 

 nary study of the American species was necessary because some of 

 the species were imperfectly known. The South American species, 

 indeed, had been identified with B. tyr annus, as only subspecifically, 

 or as specifically distinct from it. Under this confusion it was not 

 even possible to state the range of the commonest species of North 

 America. 



Genus BREVOORTIA Gill 



The Menhaden 



Brevoortuj Gill, i86i, p. 37 (genotype by designation, Brevoortia menhaden 

 Gill := 5. tyrannus (Latrobe)). 



Description. — Body oblong, compressed, median line of chest and 

 abdomen with a sharp edge, bearing bony scutes ; mouth large, the 

 maxillary extending to or beyond middle of eye; upper jaw with a 

 distinct median notch ; lower jaw included in the upper one, not pro- 

 jecting, its upper margin (within the mouth) nearly straight; teeth 

 wanting in adults; cheek (bone below eye) deeper than long; lower 

 limb of first gill arch with an obtuse angle ; gill rakers long, slender, 

 numerous, increasing in number with age, those on upper limb of 

 first arch extending downward and over those on the upper part of 

 the lower limb ; scales adherent, exposed parts much deeper than long, 

 the margins serrate or pectinate in adults ; a series of modified scales 

 next to median line of back in front of dorsal fin ; vertebrae about 42 

 to 50; dorsal with 17 to 22 rays — the last one not produced — origin 

 of fin about equidistant from margin of snout and base of caudal ; anal 

 with 17 to 25 rays ; ventral fins small, with 7 rays ; intestine very long ; 

 peritoneum black. 



Some changes that occur with age and growth. — Young, under 

 about 70 mm. in total length, have minute teeth on the margin of the 

 maxillary (verified in all the species except aurea and smithi), which 

 soon disappear with age and growth. In such young the gill rakers 

 are short and those on the upper limb of the first arch do not yet 

 extend downward over those on the upper part of the lower limb. The 

 two series of modified scales, one on each side of the median line of 

 the back in front of the dorsal fin, often do not become fully developed 

 until the young reach a total length of 100 to 125 mm. or more, and 

 the other scales have merely somewhat indented edges in the young, 

 the serrae or pectinations developing with age and growth, being 



