EXPLANATION OF PLATE XXI. 



Figures I-^METOPOLICHAS PUGNAX W. & M p. 



12, Dorsal and lateral views of an incomplete cranidium with 

 the cheeks restored in outline. 3, Dorsal view of a free cheek. 

 Both specimens from Bridgeport. (Egan Collection, Chi- 

 cago Academy of Sciences.) 4, Dorsal view of an incom- 

 plete pygidium, restored in outline. (Pal. Coll. Walker 

 Museum, No. 9,861, Van Home 



