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Cincinnati Society of Natural History. 



depressed portions of the two surfaces are sharply defined, more or 

 less elongated, depressed a maculae " or furrows, which may bifurcate 

 once or twice. The remaining portions of the surface are uniformly 

 occupied by the zocecial apertures, which, as usual, are provided with 

 a small crescentic lip. Inter-zooecial spaces occupied b}^ vesicular 

 cells, which are filled, and quite obliterated, in the " matured ' regions, 

 by a secondary deposit. 



Type : Coscinium plumosum, Prout. St. Louis Group of the Lower 

 Carboniferous. 



Beside the type species, C. elegans, C. wortheni, C. keyserlingi, and 

 C. saganella, all described by Prout, must be referred to this genus. 

 I have not seen the other species referred to Coscinium by Dr. Prout, 

 but judging from the figures in the Pal. 111., Vol. ii., PI. XXII., I am 

 inclined to think that his C. michelinia belongs here. He says of this 

 species that it is incrusting, but I regard that as very improbable. 

 If it is a double-leaved species then it is a Glyptopora, and closely 

 allied to, if not identical with, the type species. C. asteria and C- 

 eschar 'ense are very likely species of Lichenalia. 



The systematic position of Glyptopora is intermediate between Cos- 

 cinium, Keyserling, and Prismopora, Hall, but nearer the latter. 



Prismopora, Hall. 1881. 



(Bryozoans of the Up. Helder. Group.) 



Zoaria consisting of triangular branches, divided dichotomously 

 (Hall says also trichotomously) at more or less remote intervals: sides 

 equal or unequal, concave, each celluliferous. In transverse sections 

 the cells are seen to arise from internal epi thecal laminae, which radi- 

 ate from the center to each angle, and divide the branch into three 

 sub-equal triangular portions. Zooecia regularly or irregularly ar- 

 ranged, with subelliptical, oblique or distinctly lipped apertures, some- 

 times occuping the summits of small papillae. Margin of each face 

 non-celluliferous; edges straight or serrated. Interstitial spaces 

 smooth, and apparently solid at the surface; internal^, sections show 

 them to be occupied by more or less obliterated vesicular cells. 

 Diaphragms few, developed on the same level in adjacent tubes. 



Type: P. triguetra, Hall. Upper Helderberg Group. 



This genus is represented in American palaeozoic rocks b}^ at least 

 five species, and ranges in time from the Upper Helderberg Group to 



