106 ELOPIFORM FISHES 



of the interhyal. The anterior ceratohyal is somewhat constricted mid-way along 

 its length. Anteriorly the bone expands vertically and transversely. Of the two 

 hypohyals, the lower is slightly the larger. The afferent hyoidean artery ran through 

 both hypohyals and continued upon the lateral surface of the anterior ceratohyal 

 in a prominent groove. 



About 20 branchiostegals (range 18-21) are borne by the ceratohyal. Of these 

 the first five or six (the first is taken as the upper or most posterior element) are 

 broad and inserted upon the posterior ceratohyal. The anterior rays are slender 

 and articulate with the outer face of the anterior ceratohyal. The gular plate is 

 large, equal in length to two-thirds of the total mandibular length. 



Cephalic sensory canal system. The supraorbital, otic, mandibular and ethmoid 

 commissure sensory canals have been mentioned in connection with the bones through 

 which they pass. These and the other cephalic sensory canals run deep within the 

 cranial bones and the pores by which they open to the surface are often obscured by 

 heavy ornamentation. The sensory canals do not show secondary branches, a 

 point of distinction from most elopoids. 



The infraorbital sensory canal ran close to the orbital margin of the infraorbitals. 

 Anteriorly the canal terminates by a single pore at the antero-dorsal convexity of 

 the lachrymal. A short, narrow antorbital canal runs through that bone and appears 

 to end blindly. The only pores seen were those which opened within the lachrymal. 



The preopercular sensory canal ran close to the anterior margin of the preoper- 

 culum, diverging slightly from its parallel course at the angle. The canal opened 

 to the surface by 9- 11 pores situated below the angle of the canal. 



Within the supratemporal there is a canal which runs at the anterior margin and 

 represents part of the supratemporal commissure. Since the supratemporals are 

 widely separated from one another the central portion of the commissure must have 

 lain in the dermis as in Recent albuloids. Laterally the commissure opens to the 

 surface of the supratemporal by a single large pore. A canal linking the cephalic 

 sensory system with the lateral line could not be seen. 



Opercular series. All bones, except the interoperculum, are thick and ornamented 

 by radiating rugae. 



The operculum is trapezoidal in shape, with the longest edge situated anteriorly. 

 The articulatory facet which fits the opercular process of the hyomandibular is 

 near the top of this anterior edge. The facet is supported by a horizontal flange 

 which also served as a point of insertion for the levator operculi musculature. Be- 

 neath this horizontal flange there is an upwardly directed foramen, but whether it 

 penetrates the opercular bone (as does a similar foramen in Scomber, Allis 1903) is 

 not known. 



The suboperculum is large and continues the posterior border of the operculum. 

 Anteriorly the suboperculum sends up a dorsally directed wing under the anterior 

 margin of the operculum. 



The interoperculum has the form of an equilateral triangle, with the anterior point 

 lying adjacent to the articular, with which it was no doubt connected in life by liga- 

 ments. The interoperculum is distinctively short but deep. Laterally the inter- 

 operculum is largely overlain by the preoperculum. 



