FOREIGN UPPER SILURIAN. 



263 



new line among the Articulates; while Graptolites, so common in 

 the Lower Silurian, were few in species and numbers, and finally 

 became extinct before the close of the era. 



There was thus a uniformity of life in the New and Old World. 

 Similar genera made their appearance, and others their exit. In 

 neither have we any evidence that the progress had reached to the 

 introduction of land or fresh-water species of animals ; and no relic 

 of a land-plant has yet been discovered in the Silurian strata of 

 Europe or Britain, except in the uppermost beds (page 264). 



The following figures illustrate some of the British Upper Silurian species 

 not yet found in America. 



Fi<rs. 435-440. 



Fig. 435, a, Omphyma turbinata; 436, Cystiphyllum Siluriense; 437, Crotalocrinus rugosus; 

 438, Pentamerus Knightii; 439, Grammysia cingulata; 440, a, Pterygotus bilobus. 



Fig. 436 is the Cyathophylloid coral Cystiphyllum Siluriense ; fig. 435, another, 

 Omphyma turbinata, reduced one-half in size ," fig. 437, Crotalocrinus rugosus, — - 



