Fishes of the Western North Atlantic 



349 



its length to joint 1.7—2.0 in head. Upper section of Opercle with prominent radiating 

 ridges. Gill rakers very numerous; those on upper limb extending down and over 

 those on lower limb, the longest about as long as snout in adults; increasing in number 

 with age and growth, the greatest increase occurring before a loo-mm length is at- 

 tained: about 60 on lower limb in 60-mm specimens, about 100 in loo-mm fish, about 

 140 in 200-250-mm examples, and 150-160 in large adults 330— 360 mm long. 

 Teeth absent except for minute ones on margin of maxillary in young about 60 mm 

 and less. 



Dorsal fin moderately elevated anteriorly, its margin definitely concave, its longest 

 rays as long as snout and fully half of eye, the last ray somewhat longer than the pre- 

 ceding ones; origin of fin generally slightly nearer to base of caudal than to margin of 



Figure 87. Brevoortia tyrannus, modified scales in front of dorsal fin, from same specimen shown in Fig. 86. 

 Drawn by Ann S. Green. 



snout; a low sheath on base of fin, composed for the most part of a single series of 

 scales not extending above the basal third of shortest rays when standing erect. Caudal 

 rather deeply forked, the middle rays about as long as eye; the lobes rather short, the 

 lower one the longer, about as long as head, 2.8-4.0, usually 3.0—3.8, in SL. Anal 

 low, little elevated anteriorly, the margin nearly straight; its origin under or somewhat 

 behind vertical from tip of last dorsal ray, its base 5.2—7.0, usually 5.5-6.6, in SL; 

 a very narrow sheath of scales at base. Pelvic fin small, with a very gently convex 

 margin, the outermost ray only a little longer than the innermost (Fig. 84 b), the fin in- 

 serted slightly behind vertical from origin of dorsal, the length 3.1-3.8 in head. Pec- 

 toral fin slightly falcate, its length 5.0-5.9 in SL in adults, 1.6-1.9 in head, the 

 longest ray about four times the length of the shortest one, the fin generally failing to 

 reach base of pelvic in adults by a distance somewhat greater than diameter of pupil. 

 Axillary appendage of pectoral variable in length, about 75 "/o of the length of fin 

 in large examples, only about half of length of fin in examples about 100 mm long, 

 and little developed in young of 50 mm. 



Color. In fresh specimens, back dark green to bluish. Sides generally brassy and 

 sides of head bright silvery to slightly brassy. A large black spot at shoulder a very 

 short distance behind margin of opercle and well above middle of side, variable in size 

 and shape among specimens, generally roundish but sometimes vertically elongate, and 

 about as large as pupil. This spot develops first and is generally evident when the 

 fish reach a length of about 75 mm (3 in.). The shoulder spot usually followed among 

 half-grown and large examples, from about 1 50 mm (6 in.) upward, by a variable 



