Bryozoa of the Hamilton Group. 59 



. -J Fenestella fistulata, n. sp. 



Bryozoan*, broadly infuncfibuliform or cu*p shaped. 



Branches slender, gradually increasing in size to the bifurcations ; 

 bifurcations distant from five to ten millimetres; diameter of branch 

 just below bifurcation a little less than .5 mm., above bifurcation, 

 .33 mm. ; the distance between branches is less than the width, or 

 about .25 mm.; from nine to eleven branches in the space of five mil- 

 limetres ; on non-poriferous side branches slightly angular, and having 

 along the middle a narrow, slightly elevated carina or keel, which con- 

 nects with similar carina on the dissepiments ; when the dissepiments 

 or opposite ends of the branch alternate, the carina of the branch, in 

 order to connect with the carina of the dissepiments, assumes a zigzag 

 form, and also surrounds the fenestrules with a hexagonal elevation. 

 There is no evidence of striae or of nodes. 



Dissepiments comparatively strong, .25 mm. in width, expanding at 

 the junction with the branches, depressed on both poriferous and non- 

 poriferous side; on non-poriferous side, carinated and slightly angular; 

 on poriferous side rounding. 



Fenestrules small, oval ; length from .33 to .50 mm., width about two- 

 thirds the length, appearing the same size on each face of the frond. 



Cells in two and three ranges, sometimes the third range extends 

 only a short distance below the bifurcation, at others nearly the whole 

 length to the next bifurcation ; apertures, minute, circular, about 

 .12 mm. in diameter, distant from each other less than the diameter 

 of an aperture, twenty-five in the space of five millimetres, opening 

 nearly directly upward ; margins distinctly elevated, but on account 

 of the apertures opening upward, scarcely indenting the border of the 

 fenestrule ranges of apertures separated by a narrow, slightly elevated, 

 flexuous ridge, which is shorter and more prominent when there are 

 only two ranges of pores present. 



This species is one of the most abundant of those occurring in the 

 Hamilton group, and its poriferous face is generally easily recognized ; 

 from F. multiplex and F. latitruncata it is easily distinguished by its 

 size and compactness. 



Formation and localities. Hamilton group ; Genesee and Erie 

 counties, N. Y., and West "Williams, Ontario. 



/ Fenestella aspectus, n. sp. 



Bryozoan infundibuliform, undulating, frequently partially folded 

 upon itself on a line with the branches. 



Branches slender, gradually increasing in size to the bifurcations, 

 which are distant from each other from three to fifteen millimetres ; 

 a transverse section of the branch is sub-cuneiform in outliue, the 

 widest part is on the poriferous side ; just below the bifurcation on the 

 poriferous side the branch is about .5 mm. in width, gradually grow- 

 ing smaller to the non-poriferous face, where it is less than half that 

 width ; just above bifurcation on poriferous side the branch is .33 mm. 



