398 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 57 



DESCRIPTION OF PLATE 63 



PAGE 



Dikelocephalus hartti (Walcott) 368 



Fig. I. (Natural size.) Wash drawing of a large cranidium. U. S. 

 National Museum, Catalogue No. 58571. 



2. (Natural size.) Wash drawing of free cheek associated with 



fig. I. U. S. National Museum, Catalogue No. 58572. 



3. (Natural size.) Dorsal view of a small cranidium, showing the 



proportional decrease in width of the frontal rim as com- 

 pared with fig. I. U. S. National Museum, Catalogue 

 No. 58573- 



4. (Natural size.) Wash drawing of partly restored thoracic seg- 



ment, of which fig. 5 is a photographic reproduction of the 

 specimen. 



5. (Natural size.) Portion of thoracic segment. U. S. National 



Museum, Catalogue No. 58575. 



6 and 6a. (Natural size.) Dorsal and side views of a large pygid- 



ium, illustrating the increase in width of the border as com- 

 pared with the specimen represented by fig. 8. U. S. 

 National Museum, Catalogue No. 58576. 



7 and ya. (Natural size.) Photographic reproduction and wash 



drawing of a small pygidium. U. S. National Museum, 

 Catalogue No. 58577. 



Dikelocephalus ? tribulis Walcott 372 



Fig. 8. (X i-5) Wash drawing of the specimen represented by fig. 9. 

 9 and 9a. (X 2.) Dorsal and side views of the type specimen of 

 the cranidium of the species. U. S. National Museum, 

 Catalogue No. 58578. 

 10 and loa. (X 2.) Dorsal and side views of pygidium tentatively 

 referred to this species. U. S. National Museum, Catalogue 

 No. 58617. 

 The specimens represented by figs, i-io are from locality 76, 

 Upper Cambrian : Hoyt formation ; arenaceous limestone, Hoyts 

 quarry, 4 miles (6.4 km.) west of Saratoga Springs, Saratoga 

 County, New York. 



