20 



Fishery Bulletin 90(1). 1992 



SUPRAOCCIPITAL CREST 

 PTEROSPHENOID 



FRONTAL 



ETHMOID 



PTEROTIC 



LATERAL ETHMOID 



a 



FIRST VERTEBRA 

 EXOCCIPITAL 

 PROOTIC 

 BASISPHENOID 



Figure 7 



Lateral view of skulls in Grammatorcynus. (a) G. hUineatus, Scott Reef, Timor Sea, 453 mm FL; (b) G. hkariiiatus. 

 Western Australia, Exmouth Gulf, 765mm FL. 



Sclerotic The sclerotic bones consist of two 

 thickened, semicircular segments connected by carti- 

 lage on the inner surface and by corneal membranes 

 on the outside. The sclerotic bones of Grammatorcynus 

 are relatively larger and thinner compared with Scom- 

 beromorus and Acanthocybium. 



Basisphenoid The basisphenoid is a small, 

 median, Y-shaped bone that connects the prootics and 

 pterosphenoids dorsally with the parasphenoid ventral- 

 ly (Fig. 7). The dorsal compressed vertical base bears 

 a slight anterior process, but no posterior process. This 

 is similar to the condition in Scomber omorus, but the 

 anterior process is much shorter in Grammatorcynus. 



The basisphenoid is longer in G. bilineatus since the 

 height of the orbit is greater in this species compared 

 with G. bicarinatus. 



Infraorbitals The bones of the infraorbital 

 series (Fig. 10) enclose the infraorbital branch of the 

 lateral sensory canal system. The canal enters the 

 infraorbital series at what is usually considered the last 

 element (dermosphenotic), and continues around the 

 orbit, terminating on the first infraorbital (lachrymal). 

 The lachrymal, the first and largest element, is 

 elongate with a mesially-directed articular process just 

 anterior to the middle of the bone. It covers part of 

 the maxilla, and articulates with the lateral ethmoid 



