756 THE AMERICAN NATURALIST. (VoL. XXXII. 
PO 
wort 
Fic. 3. — Dinichthys intermedius Newb. Cleveland Shale, Lorain County, Ohio. Diagram 
showing cranial and dorsal shields. x ł. Lettering as in Fig. 2 
division of the central element of Brachydirus into two plates 
is to be inferred. But owing to the poorly preserved condition 
of von Koenen’s material, a confusion of sensory canals and 
sutures was easily possible; and a comparison of the remaining 
