FISHERY BULLETIN: VOL. 82, NO. 4 



d e r m o s p h e n o t i c 



cheek scales 



FIGURE 21. — Left infraorbital bones in lateral view. a. Scomberomorus maculatus, Cape Hatteras, N.C., 534 mm FL. b. Acantho- 

 cybium solandri, Revillagigedos Is., 1,068 mm FL. c. Grammatorcynus bilineatus, Timor Sea, 453 mm FL. 



as between species in the shape of the first 

 infraorbital. 



The second infraorbital (102) sits firmly on the 

 dorsal edge of the anterior portion of the first 

 infraorbital. It is a flat, somewhat compressed 

 bone. 



The third infraorbital (103) is an elongate, 

 tubular bone. It has no platelike extensions, but 

 has a large mesial shelflike extension (subocular 

 shelf of Smith and Bailey 1962). Although not 



reported by those authors, we have found this 

 shelf to occur in all species of Scomberomorus as 

 well as in all other genera of scombrids. The 

 shape of this shelf varies among specimens of the 

 same species as well as between right and left 

 sides of a single specimen. 



The fourth through the penultimate elements 

 (postorbitals) usually are simple tubelike bones 

 which may have pores accommodating canal 

 tubes to the skin and cheek scales. The fourth 



572 



