PISCES. 
79 
Order IL—ARTHRODIRA. 
During the Devonian period there flourished a race of Wall-case 
armoured fishes, which exhibit some resemblance to the true Table-cases 
Dipnoi in their teeth and appear to have agreed with the G-K. 
Fig. 81 . —Restoration of Coccosteus decipiens, left side-view, from the 
Middle Old Red Sandstone of Scotland; about one-quarter nat. size. 
(After A. S. Woodward. Wall-case 4.) 
Fig. 82 . Jaws of Dinichthys intermedius , right side, outer view, from 
the Upper Devonian of Ohio; one-third nat. size. a. anterior upper 
piercing plate ; md. mandible; p. posterior upper cutting plate ; so. 
suborbital bone, showing groove for slime-canal. (Wall-case 4.) 
latter in the fusion of the upper jaw with the skull. The 
armour of their head is movably articulated with that of the 
trunk by means of a pair of well-formed ball-and-socket 
joints, and hence they are named Arthrodira (“joint-necked ”). 
