NIAGARA FALLS AND VICINITY 



171 



non-celluliferous side oblong, quadrangular, rarely oval; branches 

 iinely striate. 



Found in the Bryozoa bed of the Rochester shale at Niagara. 

 Also in the same rock at Lockport and elsewhere (Hall). 



Genus semicoscinium Prout 

 [Ety. : semi, half (somewhat like); -/.ufT/.r^o^^ , sieve; C o s c i n - 

 i u m , a genus of Bryozoa] 



(1859. ^^ Louis acad. sci. Trans, i 443) 



Zoarium funnel-shaped, celluliferous on the outer side; dissepi- 

 ments wide, very short, the branches appearing to anastomose on the 

 non-poriferous face, where the fenestrules are subrhomboidal or 

 rounded. Apertures in two rows, with a very high median keel, 

 which is expanded at the summit. 



Semicoscinium tenuiceps (Hall) (Fig. 71, 72). Fenestella 

 tenuiceps Hall (1852. Pal, N. Y. 2:165, pi. 40D, fig. 2a-h) 

 Fenestella prisca? Hall (1852. Fal. N'. Y. 2 150, pi. 19, 

 fig. 4a-m) 



Distinguishing characters. Carina sharp and thin; transverse dis- 

 sepiments not extending as high as the branches, sometimes scarcely 



? : tf / 



If 





«.!\)5p> 



Fig. 72 Semicoscinium tenuiceps, Niag- 

 ara. Enlargements of celluliferous and 

 non-celluliferous faces 



Fig. 71 Semicoscinium tenuiceps, Clinton. Witli 

 'enlargements 



visible; round large apertures opening laterally so as to be scarcely 

 visible when looking down on the frond ; non-celluliferous side with 

 ■oval fenestrules, branches on non-celluliferous side striate, appear- 

 ing granular when worn. 



Found in the Bryozoa beds of the Rochester shales at Niagara; 

 also at Lockport (Hall) (?). It also occurs in the Clinton beds at 

 iockport, and probably also at Niagara. 



