FISHERY BULLETIN: VOL. 82, NO. 4 



a 



FIGURE 18. — Skulls in ventral view. a. Scomberomorus koreanus, Singapore, 480 mm FL. b. Scomberomorus concolor, Gulf of Cali- 

 fornia, 495 mm FL. 



The anterior margins fit neatly beside the ante- 

 rior branches of the forked ethmoid bone as can 

 be seen in the dorsal views of the skulls (Figs. 11, 

 12). They are nonprojecting in that their anterior 

 margin is at the level of the ethmoid bone except 

 in Grammatorcynus where they project well be- 

 yond the anterior end of the neurocranium (Fig. 

 13b). Length divided by width ranges from 2.0 to 

 4.2 in the three genera. The widest nasal bones 

 are in S. koreanus (2.0-2.1) and S. sinensis (2.0- 

 2.3, Fig. 20b). The most elongate nasals are in 

 Acanthocybium (3.1-4.2, Fig. 20c), Grammator- 



cynus (2.8-3.4, Fig. 20d), S. cavalla (2.8-3.1, Fig. 

 20a), and S. regalis (2.8-3.0). The other 14 species 

 of Scomberomorus are intermediate (2.0-2.9). The 

 anterior end of the nasal bone is rounded and 

 heavy in Scomberomorus and Acanthocybium 

 (Fig. 20a-c). The anterior end has a short, slightly 

 angled arm in Grammatorcynus (Fig. 20d). 



ORBITAL REGION.— The orbit is surrounded 

 by the posterior wall of the lateral ethmoid, the 

 ventral side of the frontal, the pterosphenoid, 

 sphenotic, prootic, suborbital, and lachrymal 



568 



