3 1 6 Memoir Sears Foundation for Marine Research 



of mediocris (p. 322). Both of these species are at once distinguishable from the other 

 species of Pomolobus and from Alosa by the much smaller number of gill rakers. 



Description. Proportional dimensions in per cent of standard length, and counts, 

 based on study specimens, 95—341 mm SL. 



Body: depth 24.2-28.4. 

 Caudal peduncle: depth 7.8 — 11. 

 Head: length 24.6-27.8. 

 Snout: length 4.8—6.3. 

 Eye: diameter 4.4—7.0. 

 Interorbital: width 3.8—4.8. 

 Maxillary: length 10. 5-1 2.5. 

 Pelvic fin: length 10— 12.6. 

 Pectoral fin: length 16—19. 



Scales: 51-60, often difficult to count 



accurately. 

 Ventral scutes: 33—37, most frequently 



34 or i,c^. 

 Gill rakers: on lower limb of first arch 



20—24, most frequently 20—23. 

 Fin rays: dorsal 16—21, most frequently 



18— 20; anal 1 8 —2 1 , most frequently 



19 or 20; pectoral 16 or 17, rarely 15. 

 Vertebrae: 53—55 (4 specimens). 



Body slender, compressed, its greatest thickness generally somewhat less than 

 half of its depth, its depth increasing with age and growth, usually equal to or less than 

 length of head, 3.5—4.1 in SL. 



Scales moderately adherent, with slightly irregular membranous margins, not 

 preceded by striae; 15 or 16 longitudinal rows of scales on body between base of pelvic 

 fin and anterior rays of dorsal. Ventral scutes well developed, 17—21 (most frequently 

 19 or 20) in advance of pelvics and 14—17 behind them. 



Head 3.6—4.0 in SL. Snout 4.2-4.8 in head. Eye 3.8-5.9. Interorbital 5.4— 

 7.5. Cheek, from lower rim of orbit, somewhat longer than deep. Mouth moderately 

 oblique. Upper jaw with a definite median notch in adults. Lower jaw projecting 

 strongly and extending into dorsal profile of head, its upper margin within mouth 

 rising gradually, not forming an angle (Fig. 76 a). Maxillary broad, its width 

 about 0.67 of length of snout, rounded posteriorly, reaching nearly or quite below 

 posterior margin of pupil, 2.25—2.4 in head. Gill rakers not increasing in number 

 with age. Teeth in anterior part of both jaws at all ages, those of lower jaw rather 

 prominent; sockets present if teeth are broken; teeth on tongue prominent, in a 

 rather large elongated patch. 



Dorsal fin with slightly concave margin, its origin scarcely an eye's diameter in 

 advance of pelvic and usually equidistant from margin of upper jaw and a vertical from 

 last ray of anal ; a scaly sheath on dorsal base, composed of a single row of scales and 

 extending to 4th or 5th ray from end of fin. Caudal deeply forked, the lower lobe 

 rather longer than the upper, about as long as head. Anal low, its margin nearly straight, 

 its origin usually about equidistant between base of pelvic and base of caudal ; a scaly 

 sheath present on base. Pelvic fin inserted near ventral edge and usually nearer to 

 base of pectoral than to origin of anal, 2.15-2.4 in head. Pectoral fin placed some- 

 what higher on side, 1.4— 1.6 in head. 



Color. Fresh specimens deep bluish green above, this color ceasing abruptly at 



