THE UPPER SILURIAN PERIOD. 



127 



Trimerellids ; the old and at the same time modern Lingulee, 

 Distinct, and Cranicz ; together with many species of Atrypa 



Fig. 68. Upper Silurian Brachiopods. a a', Leptoccelia plano-convexa, Clinton 

 Group, America ; b b' , Rhynchonella neglecta, Clinton Group, America ; c, Rhynchonella 

 cuneata, Niagara Group, America, and Wenlock Group, Britain; d d', Orthis elegan- 

 tnla, Llandeilo to Ludlow, America and Europe; e e, Atrypa hetnispJterica, Clinton 

 Group, America, and Llandovery and May Hill Groups, Britain ;ff, Atrypa congesta, 

 Clinton Group, America ; g g' , Orthis Davidsoni, Clinton Group, America. (After Hall, 

 Billings, and the Author.) 



(fig. 68, e}, Leptoccelia (fig. 68, a], Rhynchonella (fig. 68, b, c\ 

 Meristella (fig. 69, a, <?,/), Athyris, Retzia, Chonetes, &c. 



Fig. 69. <?, a' Meristella intermedia, Niagara Group, America ; b, Spirifera Niagar- 

 eiisis, Niagara Group, America ; c. c , Spirifera crispa, May Hill to Ludlow, Britain, and 

 Niagara Group, America ; d, Strophomena (Streptorhynchus) subplana, Niagara Group, 

 America ; e, Meristella nai'iformis, Niagara Group, America ~,f, Meristella cylindrica, 

 Niagara Group, America. (After Hall, Billings, and the Author.) 



The higher groups of the Mollnsca are also largely repre- 

 sented in the Upper Silurian. Apart from some singular types, 



