476 



HISTORICAL GEOLOGY. 



Fig. 562 represents one of the largest of Ostracoid Crustaceans, — the 

 Leperditia (?) Argenta Wale, from Argenta, Big Cottonwood Canon, Utah. 



554-561. 

 556. 558. 557. 



Trilobites. — Fig. 554, Agnostus interstrictus (4) ; 555, A. Acadicus, head and tail shields ; 556, Paradoxides 

 Harlani (|) restored; 557, P. Reglna (i) ; 558, Bathyuriscus Howelli, pygidium (2); 559, Ptychoparia 

 Kingl (1); 560, Pt. formosa, head (2); 561, Pt. Matthewi (2). Fig. 554, 558, 561, from Walcott; 555, 

 556, Meek ; 557, Matthew. 



The Caridoid Phyllopods are supposed to be represented by the Ano- 

 malocaris Canadensis of Whiteaves, a mutilated specimen of which is 

 shown, natural size, in Fig. 563. It is from the Middle Cambrian shale at 

 Mount Stephens, British Columbia. 



3. Upper Cambrian. 



The typical Upper Cambrian rocks are the Potsdam sandstone of the 

 north and east sides of the Adirondacks and adjoining parts of Canada. 

 Sandstones of the same age occur in South Dakota, Wyoming, Montana, and 

 Colorado ; shales and sandstones in Newfoundland, Cape Breton, New Bruns- 

 wick, and at some localities along the Appalachian province southwest of 



