32 



PEOCBBDIXGS OF THE 



Fig. 4. 



Osteology of Arthrodira. A. Restoration of Coccosteus decipicns. side view 

 from the Middle Old Red Sandstone of Scotland, nearlv one-quarter nat' 

 size^ B. Dentary bone of same. C. I). Ilead-sliield of Dinichfhys^ inter- 

 viedius, upper and lower view, from the Upper Devonian of Oliio, U.S A 

 about one-quarter nat. size. E. F. Jaws of same, outer and inner view.s 

 same reduction. G. Dentary bone of Diploi/vaihus mirahili^, inner view 

 from the L pper Devonian of Ohio, USA., about one-quarter nat. size.' 

 a. articulation for body-shield; br. roof of branchial chamber; d. den- 

 tary; ccf. latenil ethmoid; e.v exoccipital; mx. maxilla; orb. position of 

 orbit ; p. pmeal plate ; p,n.v. premaxilla ; so. suborbital cheek-plate ; 

 x. downward process from wall of cranium. 



