FISHERY BULLETIN: VOL. 73, NO. 3 





f 



Figure 43.— Dorsal view of glossohyals of seven species of Sar- 

 dini. a. Cybvosarda elegans, New South Wales, 355 mm FL. b. 

 Orcynopsis unicolor, Tunisia, 645 mm FL, note unequally 

 developed tooth patches, c. Sarda australis, New South Wales, 

 495 mm FL. d. Sarda chiliensis, Callao, Peru, 549 mm FL. e. 

 Sarda sarda, Tunisia, 504 mm FL. f . Gymnosarda unicolor, Truk 

 Islands, superficial tooth plate removed from left side of bone. g. 

 AUothunnus fallai, California, 680 mm FL. a-e and g drawn 

 twice the size of f . 



Figure 44.-Urohyals of five species of Sardini, in left lateral 

 view. a. Cybiosarda elegans. New South Wales, 355 mm FL. b. 

 Orcynopsis unicolor, Tunisia, 645 mm FL. c. Sarda chiliensis, 

 Callao, Peru, 549 mm FL. d. Gymnosarda unicolor, Truk Islands, 

 787 mm FL. e. AUothunnus fallai, California, 680 mm FL. a 

 drawn twice as large as b-e. 



projections which extend beyond the posterior 

 notch and their dorsal margins are flat or slightly 

 concave (Figure 45a-d). AUothunnus has no dis- 

 tinct lower projection (Figure 45f ). 



OPERCULAR APPARATUS.-Four wide flat 

 bones fit together to form the gill cover which 

 protects the underlying gill arches. 



Opercle.— The opercle is~ broad and more or less 

 rectangular in shape in all bonitos except Gym- 

 nosarda, in which it is narrower, elongate, and 

 more triangular (Figure 45e). Cybiosarda, Or- 

 cynopsis, and Sarda have similar lower posterior 



Subopercle.-The subopercle is similar among 

 bonitos and generally resembles those of 

 scombrids such as Thunnus. Cybiosarda, Or- 

 cynopsis, and Sarda (Figure 46a-d) have two 

 ridges that converge posteriorly from the anterior 

 projection. The upper ridge articulates with the 

 lower posterior projection of the opercle and the 

 lower ridge connects to the posterodorsal margin 

 of the interopercle. The ridges are much stronger 



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