ACTJNOPTEKYG1I. 



103 



pmoc. 



br. 



Fio. 73. 



Mesturus leedsi ; restoration of head and opercular apparatus, upper aspect in 

 perspective (A) and lateral aspect (B), somewhat less than one-half the nat. 

 size. U. Jurassic (Oxford Clay) ; Peterborough, ag., angular; br., branchi- 

 ostegal rays ; </, dentary ; eth., ethmoidal dermal plates ; /, frontal ; in, 

 median dermal plate; M.C., maxilla; op., operculum; orb., orbit; p. op., 

 preoperculum ; pa., parietal dermal plates ; pmx., premaxilla ; s.occ., supra- 

 occipital dermal plate; s.t., supraternporals ; spl., splenial bearing tritoral 

 teeth ; *q., squamosal ; v, vomer bearing tritoral teeth ; .r, dermal plate 

 above preoperculum. (From specimens in Leeds Collection, British 

 Museum.) 



