160 



Cincinnati Society of Natural History. 



From the former it differs in having the cell-apertures much more 

 closely arranged; from the latter it is distinguished by its less elongated 

 fenestrules; and from both by its less robust habit of growth. 



Formation and locality : In the upper part of the Cincinnati group, 

 at Oxford, Ohio. 



Phyllopora variolata, n. sp. (Plate VI., fig. 14.) 



Zoarium broadly funnel-shaped, or irregular in its growth, composed 

 of anastomosing branches, having a width of about .015 inch. Fenes- 

 trules varying from elongate elliptical to sub-circular, with a width 

 sometimes more, at other times less, than that of the branches; and a 

 length varying from once to three times the width. Cell-apertures 

 circular, arranged either in two series or three alternating rows; inter- 

 cellular spaces thin, raised into small nodes where larger; about four- 

 teen cell-apertures occupy the space ^f .1 inch. Branches on non- 

 celluliferous side smooth. 



This genus is represented by two species in the Cincinnati rocks — 

 the one above described, and another which I belive is the same form 

 that was described by Miller and Dyer under the name of Intricaria 

 clathrata (Contributions to Palaeontology, No. 2, 1878). Those authors 

 however, describe their species as having but a single row of cell-aper- 

 tures on che branches. If I am right in my identification, then that 

 statement is incorrect, since there are usually three series of cell-open 

 ings, one along the center of the branch, and another on each side. 

 The cells along the sides of the branches are easily overlooked, and in 

 specimens having the fenestrules even partially filled with matrix they 

 can not be detected, since they open almost directly into the fenes- 

 trules. 



Formation and locality: At Cincinnati, Ohio, in strata from 150 to 

 325 feet above low-water mark, in the Ohio river. 



Arthroxema, no v. gen. 



Zoarium ramose, composed of numerous slender segments. Seg- 

 ments sub-cylindrical, slightl}- swollen at each end, and celluliferous 

 on one side only; the opposite side being longitudinally furrowed and 

 striated. Cell-apertures, in two to four rows, arranged between elevated 

 lines. 



Type, Helopora tenuis, James. (Plate VI., figs. 8, 8a, 86, and 8c.) 



While making some excavations in the shales of the lower part of 

 the Cincinnati group, I was fortunate enough to discover this minute 

 and very interesting bryozoan in immense numbers. The shales were 



