364 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 64 



The largest dorsal shield has a length of 50 mm. A large cra- 

 nidium indicates that some entire specimens were at least 70 mm. in 

 length. 



The outer surface of the test is preserved on only one specimen of 

 the cranidium. This shows exceedingly fine, irregular, waving, sharp 

 elevated lines. This outer surface usually adheres to the matrix, the 

 inner layer of the test appearing smooth or punctate according to the 

 condition of preservation. 



Specimens of a cranidium and pygidium occur in Middle Cambrian 

 limestone in northern Utah that resemble those parts in Dolicho- 

 metopus boccar except that the axis of the pygidium is proportionally 

 shorter. This form was identified as Bathynriscus=Dolichometopus 

 productiis (Hall and Whitfield)/ but with our present information 

 the identification is not considered good. The best specimens of 

 D. cf. boccar are from locality (55p) Middle Cambrian: Langston 

 formation ; massive-bedded, bluish-gray limestone 44 feet ; 400 feet 

 (120 m.) above the Lower Cambrian Brigham formation; about 

 7 miles (14.4 km.) above the mouth of Blacksmith Fork Canyon and 

 10 miles (16.1 km.) east of Hyrum, Cache County, Utah. Fragments 

 of a similar form occur in the same section in the Langston formation 

 about 50 feet higher in la of the section. These were originally 

 identified as Bathyuriscus=Dolichometopus productus. 



Dolichometopus productus occurs in the Ute formation about 100 

 feet higher in i of the Blacksmith Fork section. 



Formation and locality. — Middle Cambrian: (57g, 57u) Stephen 

 formation; about 1,700 feet (518 m.) above the Lower Cambrian 

 and 3,250 feet (991 m.) below the Upper Cambrian, in the calcareous 

 shales forming 2d of the Stephen formation," on Mount Bosworth, 

 north of the Canadian Pacific Railway between Hector and Stephen, 

 on the Continental Divide between British Columbia and Alberta ; 

 (14s) near the base of the Ogygopsis zone of the Stephen formation, 

 just east of the great " fossil bed " on the northwest slope of Mount 

 Stephen, above Field, on the Canadian Pacific Railroad, British 

 Columbia; (58m) about 1,000 feet (305 m.) above the top of 

 the Lower Cambrian in bluish-black and gray limestone (138 feet) 

 of the Stephen formation, Castle Mountain section ; northeast slope 

 of Castle Mountain, facing amphitheater, north of Canadian Pacific 

 Railway, Alberta; and (6ir') formation unknown; from a block on 



Smithsonian Misc. Coll., Vol. 53, igoS, p. 198. List under la and ib. 

 Idem, Cambrian sections of the Cordilleran area, p. 211. 



