NO. 3 



TELEOSTEAN FISHES GOSLINE 



27 



In Elops both bones are present (Nybelin, 1957, fig. 2) but do not 

 seem to form a movable link, for the supraorbital bone is tightly at- 

 tached to the frontal; there is no supraorbital nasal sac (Derschied, 

 1924, fig. i,c). Me gal ops differs only slightly in the possession of a 

 small supraorbital nasal diverticulum (Derschied, 1924, fig. 3). In 

 Albula there is an elongate, movable supraorbital bone associated 

 with a canal-bearing antorbital (as in Pterothrisstis, fig. 7B) ; the 

 supraorbital diverticulum extends well back under the former bone 

 (Derschied, 1924, fig. 4,&). 



,^^ME 



Fig. 8. — A, Snout region of Pellona sp. (Qupeiformes). 



B, Ethmoid region of cranium of Mycteroperca (Perciformes). FR, frontal; 

 LE, lateral ethmoid ; ME, mesethmoid ; VO, vomer. 



C, Snout region of Mycteroperca (Perciformes). CA, cartilaginous area 

 under premaxillary pedicels ; em, ethmoid-maxillary ligament ; ME, mesethmoid 

 bone; MX, maxillary bone; PA, palatine bone; PM, premaxillary bone; pp, 

 palatine-premaxillary ligament ; pr, interpremaxillary ligament. 



In Alepocephalus there is no supraorbital bone and no supraorbital 

 nasal diverticulum of the nasal capsule (Derschied, 1924, fig. 11). 

 There is however an L-shaped antorbital which protects the ventral 

 and posterior borders of the nasal openings, but there is no liga- 

 mentous connection between its forward end and the maxillary. 



Among the herringlike fishes the suborbital and supraorbital nasal 

 sacs are usually both represented (Derschied, 1924, pp. 98-106, figs. 

 6-8). The antorbital-supraorbital link is always present (fig, 8A) 

 and perhaps reaches the epitome of its devlopment as a pumping 

 mechanism (Kirkhoff, 1958). Nevertheless, even among this group 

 there seems to be considerable reduction in the size of the diverticula 

 and in the mobility of the dermal bones of the snout in those forms 

 with a heavy covering of adipose tissue in the snout region, e.g., 

 Dorosoma and the anchovies. Indeed, in the anchovy examined the 

 supraorbital appears to be rigidly united to the skull. 



