or is directed toward in scleratus and inermis. No such 

 flange is present in lagocephalus, but the area of contact 

 between the especially long posterolateral prolongations 

 of both the frontal and pterotic is much greater than in 

 the other species. 



The ethmoid in Lagocephalus is relatively long in all 

 six species, but its width varies from moderate in 

 scleratus and lunaris to wide (the other four species). 

 Anteriorly the ethmoid always broadly sutures with the 

 dorsal surface of the vomer, and, as explained for 

 laevigatas in the detailed osteological description, this 

 articulation sometimes becomes fully fused in large 

 specimens. In laevigatas the ethmoid and the haemal 

 spines of the sixth and seventh, and, to a lesser extent, of 

 the eighth, caudal vertebrae become swollen or hypero- 

 stotic in large adults. The only other species studied here 

 as a large adult specimen, a 214 mm lagocephalus, does 

 not show any hyperostosis, but the specimens oi inermis, 

 lunaris, scleratus, and spadiceas studied are all too small 

 to have hyperostotic parts even if that should be the 

 norm for large adults. 



The supraneural element is relatively long in most 

 species of Lagocephalus, while it is extremely long in 

 lagocephalus and only moderately long in inermis. 

 Medial prongs from the prootic in the rear of the orbit, 

 representing the remains of the dorsal roof of the 

 myodome, are well developed in scleratus and 

 laevigatus, reaching almost to the midline, and are 

 moderately developed in lunaris and spadiceus, while 



Figure 260.— Dorsal views of skulls of: 



A, Sphoeroides greeteyi, 60.8 mm SL, locality 



unknown: B, S. trichocephalus, 57.1 mm SL, Panama (Pacific); 



C, S. pachygaster. 117 mm SL, Mozambique. 



they are absent in inermis and lagocephalus. The 

 amount of surface sculpturing (not fully shown in the il- 

 lustrations) of the top of the skull varies from slight in 

 scleratus to moderate or well developed in the other 

 species. This, however, may be subject to intraspecific 

 variation or change with increasing specimen size, for 

 Kuronuma (1943) reported that lunaris and spadiceus, in 

 contrast to inermis, had little surface sculpturing, mostly 

 confined to the ethmoid. 



The modal number of vertebrae in Lagocephalus is 17 

 {lunaris, scleratus, spadiceus), 18 (inermis, lago- 

 cephalus), and 19 (laevigatus), with the lower numbers 

 more specialized. Neural prezygapophyses, especially on 

 the caudal and more posterior abdominal vertebrae, are 

 extremely well developed as anterolaterally directed 

 prongs in lagocephalus and scleratus, the two most 

 streamlined and probably rapid swimming species, but 

 are only moderately developed in the other four species. 

 Likewise associated with muscle attachment are keels or 

 ridges along the dorsolateral region of the neural arches 

 (and, to a lesser extent, along the ventrolateral region of 

 the haemal arches of the caudal vertebrae). These keels 

 are well developed in lagocephalus and scleratus, 

 moderately developed in laevigatus and spadiceus, and 



