﻿American Palaeozoic Fossils. 



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perforated at rythmical intervals by circular or elliptical fenestrules 

 Both sides of the zoaria are celluliferous, and the fronds consist of 

 two equal layers of cells, that have grown together back to back, but 

 in such a manner, that each layer preserves its own concentrically 

 striated epithecal membrane. A smooth or finely striated non-cellu- 

 liferous border surrounds the fenestrse. Zooecia with sub- circular or 

 elliptical apertures, that are slightly oblique, and provided with the 

 usual small lip on the outer margin. Inter-zooecial spaces occupied 

 by unequal vesicular cells, which, near the surface, are filled by a 

 secondary deposit, vertically perforated by numerous minute com- 

 municating canals. Diaphragms not observed. 



Type: C. cy clops, Keyserling. The genus, so far as known, occurs 

 only in Devonia deposits. 



Hall's genus Clathropora is usually regarded as S3mon} T mous with 

 Coscinium, but that is an error. While the form of the zoarium in 

 the two genera is almost identical, their cell structure, and internal 

 characters generally, are totally unlike. The minute characters of 

 Clathropora frondosa, Hall, which must be considered as the type of 

 the genus, prove Clathropora to be an unquestionable member ot the 

 Ptilodictyonidm, since the cell structure of that species is, in almost 

 every particular, precisely like that of the most typical species of 

 Ptilodictya. Some authors would perhaps on this account unite 

 Clathropora with Ptilodictya, but I believe that this is a case wherein 

 the difference in the mode of growth should be regarded as of generic 

 importance. 



Prout has described a number of Lower Carboniferous Bryozoa, as 

 species of Coscinium. I can not see that any of these realty belong 

 to that genus, although the most of them belong to the Cystodicty - 

 onidoB. For their reception I propose the new generic name of 

 Glyptopora. 



Glyptopora, n. gen. 



Zoaria forming thin, leaf-like expansions, composed of two sub- 

 equal layers of cells, adhering to each other back to back. Both 

 surfaces celluliferous, with an elevated, sharp midrib, or ridge, which 

 may simply divide dichotomously at varying intervals, or inosculate 

 more or less frequently, so as to leave irregular cup-shaped depres- 

 sions. The sharp margin of this ridge is non-poriferous, and may be 

 either straight or serrated. Distributed with some regularity over the 



