CORALS AND BRYOZOA. 147 



branches, strong ; width .33 to .38 mm., angular, slightly carinated, seven 

 in the space of 5 mm., on a plane with the branches or elevated above them; 

 sometimes continuing across the branches and uniting with adjacent dissepi- 

 ments, forming irregular, continuous elevations, which are very prominent, 

 but do not obscure the branches. Fenestrules oval, length from .33 to .38 

 mm., width .25 mm. 



On the celluliferous face the branches are straight : dissepiments rounded 

 or sub-angular, slightly carinated, depressed. Fenestrules much narrower 

 than on the opposite face, the length being frequently as much as three times 

 the width. Cell apertures in two ranges, opening directly outward, twenty- 

 five in the space of 5 mm., separated by less than half the diameter of an aper- 

 ture : margins remarkably elevated, attaining a height of .10 mm., indenting 

 the borders of the fenestrules; carina .40 mm. high; summit sometimes 

 sharp, at other times .10 mm. wide. Scalae and pseudo-carinae, usually slightly 

 narrower than the carinae, twelve scalaa in the space of 5 mm. Interstices 

 nearly circular or sub-quadrangular ; frequently the summits of the carinaB 

 are sharp and irregular, this face of the frond then having the appearance 

 of some form of Paleschara. (In fact, some authors have mistaken similar 

 forms for incrusting corals.) The carina is apparently formed from the con- 

 necting of a row of small columns by a thin plate ; when this is removed 

 there is no evidence that the thinner portion proceeded from the branch, the 

 base having very much the appearance of a row of nodes or cell apertures. 

 This face of the frond with the carinae removed, might be very easily mis- 

 taken for some form having three rows of cell apertures. 



The non-celluliferous face of this species so closely resembles F. {Unitrijpa) 

 stipata, that it is not possible to satisfactorily distinguish them. The celluliferous 

 faces are, of course, very different. From F. {Hemitry pa) favosa or F. {H.) nana, 

 it is distinguished by its stronger branches and very much stronger dissepi- 

 ments ; from F. {H.) cribrosa by its much stronger dissepiments ; from F. (H.) 

 biordo, by its more slender branches, more closely disposed branches and dis- 

 sepiments and much smaller fenestrules. 



Formation and locality. Upper Helderberg group, Walpole, Ontario, Canada. 



