454 MR. C. TATE REGAN ON THE 



Except that the palatine is separable into an endosteal 

 ossification and two dentigerous laminae, the ptery go- quadrate, 

 hyoid, and opercular bones are the same as those of Lepidosteus-, 

 but they are very differently arranged, for the metapterygoid is 

 firmly attached to the hyomandibular and the quadrate to the 

 symplectic, the well-developed crescentic prseoperculum is united 

 to the hyomandibular and symplectic, and the interoperculum is 

 normally developed and movable. Some authors have described 

 a process of the metapterygoid as articulating with the pi-o,- 

 otic, but actually there is no such articulation, and the process, 



Text-figure 8. 



Sa?7 



cCeit 



cin 



an 



Amia calva. Lower jaw, inner and onter aspects. 

 Lettering as in text-fig. 5. 



which is an intermuscular lamina directed upwards, forwards, 

 and outwards, does not go anywhere near the otic region of 

 the skull. 



• Amia has a good series of branchiostegal rays and a median 

 gular plate. The ceratohyal has two ossifications and the hypo- 

 hyal one as in Lepidosteus, and the branchial skeleton shows 

 no important differences from that genus. 



Vertekrce and fins. — The vertebral column of Amia is well 

 known; the most important differences from Lepidosteus are 

 that the vertebrte are amphicoslous, and that in most of the 



