420 BULLETIN 189, UNITED STATES NATIONAL MUSEUM 



North Island. The species is characterized chiefly by the small scales, 

 posterior insertion of the ventral fins, and the rather short pectoral 

 fins. 



Range. — Galdpagos Island, and coast of Peru, 



Family MUGILIDAE: Mullets 



Body elongate, more or less compressed; mouth moderately small, 

 with or without small teeth; premaxillaries protractile; gill openings 

 wide, the membranes separate and free from the isthmus; gills 4, a 

 slit behind the fourth; gill rakers long and slender; scales large; no 

 lateral line; two short, well-separated dorsal fins, the first with four 

 stiff spines; second dorsal longer than the first; anal with two or 

 three graduated spines; caudal forked; ventrals abdominal, with one 

 spine and five soft rays, 



A single genus comes within the scope of the present work. 



Genus MUGIL Linnaeus, 1758 



Head large, about as broad as deep in adults; eye with much adipose 

 tissue in large examples; mouth broad, oblique; lower jaw included, 

 angulate; teeth present on jaws only, small and flexible, often in one 

 or a few series, occasionally in a band; scales rather large, firm, extend- 

 ing forward on head, and generally more or less on the fins; anal fin in 

 young, under about 50 to 60 mm. long, with two spines, adults con- 

 stantly with three; stomach with heavy muscular walls, gizzardlike. 

 The mullets often have been described as "mud eating fish," the mud 

 being ingested chiefly for its diatom content. The genus is of wide 

 distribution, occurring in all warm seas. Some of the species are of 

 great commercial value. 



Five species seem to belong to the fauna of Peru. 



KEY TO THE SPECIES 



a. Anal normally with III, 8 (j^oung II. 9) rays; fins, except caudal (in one 

 species), not densely scaled, the scales on fins not increasing greatly in 

 density with age. 

 h. Teeth in each jaw in a rather broad band; mouth broad, its width at angles 



generally exceeding the length of maxillary rammelsbergii (p. 421) 



bh. Teeth in jaws not in broad bands. 



c. Teeth in upper jaw generally in a single series, occasionally in a very 

 narrow band; scales rather smooth, without prominent concentric rings, 

 present on base of caudal only; mouth moderately narrow, its width 



generally about equal to length of maxillary cephalus (p. 422) 



cc. Teeth in upper jaw in 2 well-separated series; scales more or less rough to 

 the touch, with prominent concentric rings, many with serrated mar- 

 gins, scales covering most of the caudal fin; width of mouth equal to or 

 slightly exceeding length of maxillary .peruanus, new species (p. 424) 

 aa. Anal normally with III, 9 (young II, 10) rays; fins, exclusive of spinous dorsal 

 densely scaled in adults. 



d. Upper lip thin; scales 35 to 40 curema (p. 426) 



dd. Upper lip thick; scales 45 or 46 thobumi (p. 428) 



