368 



THE OSTRACODERMS. 



way into the head at this place that could be opened and closed by the movements 

 of this plate, and there is no reason for regarding it, either functionally, or morpho- 

 logically, as an operculum. 



FIG. 247. -Restoration of Bothriolepis canadensis (Whiteaves; from Miguasha, P. Q., Canada.) Neural surface; 



about 1/2 natural size. 



The anterior end of the suspensory plate is narrow and slightly curved, 

 and adjoins a small quadrangular, movable plate that probably represents the 

 maxillary plate of the arthrodira. In depressed heads, it is bent over onto the 



