208 PALEONTOLOGY OF NEW YORK. 



strongly and regularly corrugated ; corrugations sharp, five in the space of 

 1 mm. Septa extremely thin, in some cells moderately frequent, in others 

 obsolete. Intercellular tissue vesiculose ; the vesicles near the base are large 

 and very irregularly disposed, they are smaller above and more regularly 

 superimposed, frequently having the appearance of septate tubuli, with strongly 

 corrugated walls. A transverse section shows the cells to be cylindrical, 

 frequently partially in contact and the ordinary cells never distant more than 

 .10 mm. Cell apertures circular, diameter .30 mm., very closely and usually 

 irregularly disposed, but sometimes forming sub-regular curved lines on the 

 monticules, generally distant a little more than one-fourth the diameter of 

 an aperture. Peristomes usually obsolete. Inter-apertural space elevated 

 angular, sometimes with minute nodes at the angles, giving to the apertures 

 a polygonal appearance, much resembling those of some form of Favosites. 

 Surface marked by broad, convex monticules, the centers of which are distant 

 from 5 to 8 mm., and have a granulose circular area, about 1.75 mm. in 

 diameter, destitute of cell apertures. The apertures immediately adjacent 

 are a little larger and more distant than the others, a little oblique and with 

 very thin peristomes, the posterior portions of which are the stronger, with 

 evidences of very slight denticulations ; the space between these apertures 

 is somewhat flattened and sometimes with a very slender striation. 



This species may be distinguished from Fistulipora conslrida by the broader, 

 more distant monticules, the larger cell apertures, destitute of peristomes 

 and denticulations, the smooth interapertural space and the absence of 

 mesopores : from F. unilinea it is distinguished by the more prominent monticules, 

 the absence of peristomes and denticulations and the angulated inter-apertural 

 Bpace without mesopores ; nearly the same features will distinguish it from F. 

 interaspera. From any other species at present known, in the Lower and 

 Upper Helderberg and Hamilton groups, it may be distinguished by the circular, 

 closely disposed cell apertures without peristomes or denticulations, and the 

 smooth angular, inter-apertural space, giving to the apertures an appearance 

 similar to those of some forms of Favosites. 



Formation and locality. Hamilton group, Genesee Valley, N. Y. 



