GENEEAL GEOGRAPHIC AND STRATIGRAPHIC DISTRIBUTION. 



Summary of Cambrian Brachiopoda hy genera — Continued. 



Ill 



a One species passes from the Upper Cambrian to the Ordovician. 



& Two species pass from the passage beds to the Ordovician. 



c One species passes up from the Lower to the Middle Cambrian; two from the Middle to the Upper Cambrian; and one from the Middle Cam- 

 brian to the passage beds. 



d Two species pass from the Middle to the Upper Cambrian and one species passes from the Upper Cambrian to the Ordovician. 



e Six species pass from the Middle to the Upper Cambrian, of which one continues on into the passage beds; one species passes from the Lower 

 to the Middle Cambrian, and one from the Upper Cambrian to the passage beds. One species is conunon to the Middle and Upper Cambrian and 

 to the Ordovician; one species is common to the Upper Cambrian and the passage beds; and one species passes from the Upper Cambrian to the 

 Ordovician. 



/ Two varieties pass from the Middle to the Upper Cambrian and one variety is coromon to the Middle Cambrian, Upper Cambrian, and 

 passage beds. 



g Two species pass from the Middle to the Upper Cambrian of which one continues into the Ordovician. One species passes from the Lower 

 to the Middle Cambrian. 



ft One species passes from the Middle to the Upper Cambrian; one species is common to the Upper Cambrian, passage beds, and Ordovician; 

 one species is common to the Middle Cambrian, Upper Cambrian, and Ordovician; one species passes from the Upper Cambrian to the passage 

 beds; one variety is common to the Upper Cambrian and the Ordovician. 



i One species is conunon to the Upper Cambrian and the Ordovician. 



