Bryozoa of the Hamilton" Group. 61 



Dissepiments comparatively strong, , about .25 mm. in diameter, 

 expanding at their junction with the branches, nine or ten in the space 

 of five millimetres ; on non-poriferous side rounded, nearly on a plane 

 with the branches, granulose; on poriferous side depressed slightly 

 below the ranges of apertures. 



Fenestrules on non-poriferous side broadly oval, appearing narrower 

 on poriferous side ; length about .5 mm.; width from one-half to two- 

 thirds the length. 



Cells in two ranges, opening at an angle of forty-five degrees from 

 the axis of the branch ; apertures small, circular, about .14 mm. in 

 diameter; distance apart less than the diameter of an aperture, twenty- 

 eight to thirty in the space of five millimetres ; apertures distinctly 

 elevated and indenting the border of the fenestrules ; space between 

 the ranges of apertures carinated ; carina sharp, slightly elevated, 

 and having prominent nodes or short spines, four in the space of one 

 millimetre. 



To the poriferous side of F. fistulata this species has no resemblance; 

 it slightly resembles the non-poriferous side, from which, however, it is 

 readily distinguished by the absence of the keel along the middle of 

 the branch and on the dissepiments, and by the presence of striations, 

 nodes and granules. 



Formation and locality. Hamilton group ; Alden, Erie Co., X. Y. 



/ • Fenestella marcida, n. sp. 



Bryozoan, consisting of large infundibuliform fronds, frequently' 

 undulating or partially folding upon itself along the line of the 

 branches. Branches slender, very gradually enlarging to the bifurca- 

 tions, which are distant from each other from seven to twenty-four 

 millimetres ; width below bifurcation .33 mm. ; width just above bifur- 

 cation .25 mm. ; distance from each other equal to or a little more than 

 the width of the branches, sometimes appearing less on poriferous 

 side than on non-poriferous ; on non-poriferous side branches rounded, 

 except just below bifurcation, where they are flattened, striated ; striae 

 fine but distinct, finely granulose, from three to five on a branch. 



Dissepiments about .20 mm. wide, eight in the space of five milli- 

 metres ; on some fronds the width is .25 mm., nearly equal in width 

 to some parts of the branches, expanding slightly at their junction 

 with the branches ; on non-poriferous side depressed, striated ; stria? 

 granulose ; on poriferous side slightly depressed, rounding, carinated ; 

 carina very thin, slightly elevated. 



Fenestrules broadly oval, occasionally subquadrangular ; length 

 nearly .5 mm.; width two-thirds the length; on porilerous side the 

 fenestrules appear narrower, the width often not more than one-third 

 the length and sometimes appearing only as a narrow slit. 



Cells in two ranges, apertures small, circular; diameter about one- 

 seventh of one millimetre ; distant from each other less than the di- 

 ameter of an aperture, seven to eight in the space of five millimetres ; 

 margins distinctly elevated and indenting the border of. the fenestrule ; 

 space between ranges of apertures carinated ; carina spinulose ; nodes 



