78 



Mr. R. Walker on Fossil Fishes of Dura Den. 



there is a row of small slightly hooked teeth extending round 

 its lower border. 



The lower jaws appear to be strong, and are somewhat power- 

 ful-looking bones : there are two distinct rows of plates on each 

 side between the rami and the two centi*al jugular plates; the 



Fig. 4. 





!»q 



Crushed head of H. Flemingii. 



outermost row is the largest; their exterior margins seem to have 

 been overlapped a little by the inferior edge of the rami, while 

 they in turn overlapped the margins of the next ; these plates 

 are longer than broad, and meet each other by oblique sutures 

 passing inwards. The inner row of plates is about half the 

 breadth of the outer, and they join together by more transverse 

 sutures. These plates or bones are continued back, and turned 

 up, on the sides of the head, behind the articulation of the infe- 

 rior maxilla, till they terminate below the inferior margin of the 

 sub-operculum. 



So far as I can perceive, the cranium above described does 

 not appear to differ in any respect from that of H. Ander- 

 soni : the head of the latter species is not, in general, so well 

 preserved ; but so far as the bones are exposed, they seem to me 

 to be the same in number, arrangement, and shape. Neither 

 does it differ materially from the bones of the head of Glypto- 

 pomus, as figured by Prof. Huxley; in fact, the resemblance in 



