ACTINOPTERYGI1. 83 



is flanked on each side by a so-called anterior frontal element 

 (a./.), and with the latter surrounds the pair of narial openings 

 (.). The parasphenoid is well developed. The maxilla (mx.) 

 is a narrow, elongated element, always much expanded behind ; 

 the premaxilla (pmx.) is comparatively small. A narrow ring 

 of about four circumorbital bones surrounds the" eye, and these 

 are bounded behind by other cheek-plates of the suborbital 

 series (s. o.). The preoperculum (p. op.) also extends forwards 

 upon the cheek. In the mandible the articular portion of the 



\p.cl 



Paltconiscus macropomus ; head and pectoral arch, restored in outline by E. H. 

 Traquair, about nat. size. U. Permian ; Thuringia. o./., anterior frontal ; 

 ag., angular ; fcr., branchiostegal rays; cl., clavicle ; d, dentary; e, ethmoid; 

 /, frontal; i.cl., infraclavicle ; i.op., suboperculum ; mx., maxilla; n, narial' 

 opening; op., operculum ; p, parietal; p.cl., postclavicle ; p. op., pre- 

 operculum; p.t., post-temporal; pmx., premaxilla; q., squamosal; s.cl., 

 supraclavicle ; s.o., circumorbital ring and suborbitals ; s.t., supratemporaL 

 Dotted lines indicate course of mucus-canals. 



meckelian cartilage is ossified, and the rest is ensheathed 

 outside by a large dentary (d.) and a small angular (ag.), while 

 its inner face is equally covered by an extensive laminar splenial. 

 No symplectic bone has hitherto been observed, though the 

 hyomandibular is sometimes shown. The pterygo-quadrate 

 seems to be ossified at least at the quadrate articulation ; and 

 there is evidently a large, elongated membrane-bone en- 

 sheathing its inner or oral aspect. There is no interoperculum, 

 but the operculum, suboperculum, and branchiostegal rays are 



62 



