BRYOZOA—CRYPTOSTOMATA. 



149 



four rows of oval and alternating apertures, on the celluliferous 

 side ; dissepiments thin, scarcely thickened at junction with 

 branches. 



Rochester shale of New York and Canada. 



104. P. fistulata (Hall). Mid-Devonic. 

 Two to three rows of apertures with strong peristomes ; fenes- 



trules oval, dissepiments expanding at the ends. 

 Hamilton of New York and Ontario. 



105. P. shumardi Prout (P. cultellata Hall). Mid-Devonic. 

 Strong branches united by their dissepiments, forming narrow 



fenestrules on celluliferous side, where branches are marked by 

 sharp nodes, and have from three to seven ranges of apertures ; 

 reversed side with broad oval fenestrules, and a faint keel or nodes, 

 or smooth. 



Hamilton of Falls of the Ohio. 



Fig. 205. a, Archimedes worlheni, y<*4 ; b, A. sublaxus, showing fenestrated por- 

 tions, X % > &' * A communis, two specimens, X 72. '■> c > Polypora submarginata, obverse 

 face, X4/^ > ^> Lyropora quinconcialis, poriferous face, X4/^» d f > obverse side of basal 

 support, X 72. > e > Thamniscus furcillatus, obverse face, X %. an d X 9 \f* Pinnato- 

 pora conferta, X X an( ^ X 4 72. \ g, Ptilopora cylindracea, obverse face, X K an( ^ 

 X A72. > &> Diploporaria bifurcata, X A72 5 z » Arthrostylus obliquus, lateral and non- 

 celluliferous aspect, X 9 5 j\ Helopora spiniformis, X 72. an <i X 9 '> k, Arthroclema 

 billingsi, frond, X 72. \ 1> A. armatum, segment of primary series with articulating 

 socket, X 72. an d X 9- (After Ulrich. ) 



