ON MEGALICHTHYS 313 



The specimen exhibits the usual tuberculation characteristic 

 of AT. coccolepis. It is difficult to determine some of the 

 apparent sutures in this portion of skull fragment. The skull 

 has been flattened so as to tend to close the sutures between 

 the elements. The following interpretation may be suggested : 

 Unlike the anterior portion of the skull of AT. hibberti B7* 

 {infra) the example before us has the compound ethmoidal 

 shield divided by sutures into its constituent bones. The 

 pre-maxillae are seen to meet in a somewhat curved median 

 suture. The median ethmoid {vide B6* infra) seems to have 

 become fused with the right nasal, and, as in other cases, there 

 seems to be a tendency for the bones on the left side to be at 

 a more advanced stage of fusion than those on the right. 



Megalichthys hibberti : B6*, anterior portion of 

 skull. (Plate XV., fig. 1 ). 



This represents a less advanced stage in the course of fusion 

 of the head bones than is the case in B5* {ante). The bones 

 have been much flattened out. Near the centre of each pre- 

 maxilla is a small depressed area. 



Megalichthys hibberti: B7*, anterior portion of skull. 



B7* shews a more advanced stage in the fusion of head bones 

 than does B5*. The depressions seen in many specimens are 

 here very marked, and in the case of the right depression 

 there is an opening into the buccal cavity from the dorsal 

 surface of the skull. The anterior portion of the dorsal surface 

 of the skull, although cracked, is well preserved. The hinder 

 portion is less well preserved, and is decorticated. 



Megalichthys hibberti : B13*, anterior portion ofskull. 



This exhibits part of the " compound ethmoid " of 

 M. hibberti. No sutures are visible, and there are the two usual 

 large depressions near the lateral borders of the shield. The 

 specimen is fairly well preserved. 



