174 PALJEONTOLOGY OF NEW YORK. 



Fenestella (Ptiloporina) sinistralis, n. sp. 



PLATE XUII, FIG. 9. 



Bryozoum infundibuliforra, length of the largest fragment observed 65 mm. 

 with a width of 75 mm. The primary branches, commencing at the base, 

 do not increase in size, but have a uniform width of about .60 mm. ; the 

 secondary branches have a width of about .30 mm., some of these, on the frag- 

 ments observed, continuing their entire length without increase in size, while 

 others attain a width of .60 mm. and have smaller lateral branches ; all these 

 are straight, angular and slightly carinated ; the primary branches are 

 strongly elevated above the others. Interstices a little wider than the 

 secondary branches. Dissepiments slender, width about .35 mm., angular, 

 slightly carinated, on a plane with the secondary branches, six in the space 

 of 5 mm. Fenestrules oval, length a little less than .60 mm., width .35 to 

 .40 mm. 



On the celluliferous face the dissepiments are rounded and depressed. 

 Fenestrules slightly narrower than on the opposite face. Cell apertures in 

 from two to five ranges, two ranges occur only immediately above a bifur- 

 cation, opening outward and laterally, eighteen in the space of 5 mm., 

 separated by less than the diameter of an aperture : margins elevated, in- 

 denting the borders of the fenestrules. 



This species may be distinguished from F. (Ptiloporina) disparilis by its second- 

 ary branches, dissepiments and fenestrules, and the more compact appearance of 

 the frond ; from F. {Ptiloporella) laticrescms by its secondary branches, closer dis- 

 position of the dissepiments, and by the greater number of ranges of cell aper- 

 tures, that species having only two ranges ; from F. {Ptiloporella) inequalis it is 

 distinguished by its larger branches, dissepiments and fenestrules, the greater 

 number of ranges of cell apertures, that species having only two ranges, and 

 by the coarser appearance of the frond. From all other similar species, at 

 present known, in the fact that the secondary branches proceed only from the 

 left side of the primary branches. 



Formation and locality. Upper Helderberg group, Schoharie grit, Schoharie, 

 N. Y, 



