ON MEGALICHTHYS 



321 



sloping margin, which is overlapped by another scale ; the 

 fore edge was sunk in the skin, and also overlapped. The 

 scale is thickest at its centre. 



The skull is long, broad, and depressed. The orbits are 

 far forward. The nasal apertures are in front of them at the 

 sides of the rostrum. The top of the brain case is protected 



Text-figure 3. Megalichthys hibberti. Restorations of the head. 

 (S. Graham Birks del.) A. Superior aspect. B. Inferior aspect. 

 C. Side view. 



C. eth., compound ethmoidal shield ; so., sub-orbitals ; fr., rontals ; 

 mx., maxillae ; x and x\ cheek-plates ; par., parietals ; p.f., post-frontal 

 element ; sq., squamosal element ; p.op., pre-operculum ; op., operculum 

 s.t., supra- temporals, or nuchal-plates ; mn., mandible : j., principal 

 jugulars; m.j., median jugulars; l.j., lateral jugulars; s.op., sub- 

 operculum ; op", op."', inferior operculars. The orbit is shaded. 



by a parietal shield which is often defined on the sides as well 

 as behind by an irregular sunk space, which indicates sub- 

 sidence and a weak condition of the underlying parts, a 

 feature which accounts for the frequent loss or crushing of the 

 dermal bones of the disturbed regions. The parietal region 



