BRACHIOPODA. 



35 



The presence of the median septum establishes another line of connection 

 with the post-palaeozoic members of the genus Spiriferina, while the punctation 

 of the epidermal layer only, retains these fossils in close association with the 

 glabrate Spirifers. 



The following table will afford a summary of the foregoing classification as 

 far as it relates to the North American Spirifers. The names of species of 

 which specimens have been examined stand in Roman text ; those which have 

 been placed in the grouping from a study of descriptions and illustrations only, 

 are in italics ; others, in regard to whose relations it has seemed unwise to ex- 

 press an opinion on account of the insufficiency of our knowledge, are omitted. 

 Any names of extra-liinital species stand in brackets. 



I. Radiati : 



1 . Pauciplicati : 



S. radiatus, Sowerby, 



S. Eudora, Hall, 



S. Meta, Hall, 



S. Foggi, Nettelroth, 



S. rostellum. Hall and Whitfield, 



S. macropleura, Conrad, 



2. Multiplicati : 



S. Niagarensis, Conrad, 

 S. asperatus, Ringueberg, 

 S. Tullius, Hall, 

 S. Belphegor, Clarke, 

 S. mesastrialis. Hall, 

 S. sp. indes., 



3. Dupliciplicati : 



S. nobilis, Barrande, 

 [S. Schmidti, Lindstrum, 



II. Lamellosi: 

 1. Septati: 



S. sulcatus, Hisinger, 

 S. perlamellosus. Hall, 



Clinton and Niagara groups. 



Niagara group. 



Niagara group. 



Niagara group. 



Niagara group. 



Lower Helderberg group. 



Niagara group. 

 Niagara group. 

 Hamilton group. 

 Genesee shale. 

 Chemung group. 

 Lower Carboniferous. 



Niagara group. 

 Wenlock limestone.] 



Niagara group. 



Lower Helderberg group. 



