BRYOZOA. 549 



FEXESTELLA ELEVATIPORA Ulrich. 



PI. LI, Figs. 3-3a. 



Zoariurn a flat foliar expansion, of which only small frag- 

 ments have been seen. Branches rigid, closely approximated, 

 0.25 to 0.3 mm. in width, twenty-five or twenty-six in 1 cm. 

 Dissepiments short, slender, so much depressed that they are 

 easily overlooked on examples adhering to the rock or shale. 

 Fenestrules small, irregular in shape, about two and one-half 

 times as long as wide, with about twenty-four in 1 cm. Obverse 

 side of branches comparatively flat. Carina small, thread-like. 

 Zooecia in two ranges, twenty-six in 5 mm. Apertures circular, 

 directed outward, pustuloid, the peristome being very promi- 

 nent; generally two to each fenestrule. On the reverse the 

 branches are rounded and occupied by from three to five thread- 

 like longitudinal striae, the fenestrules longer than on the ob- 

 verse, and subquadrate in form. 



The more strongly striated reverse, the less convex and some- 

 what wider obverse face of the branches, and their crowded ap- 

 pearance separate this species from its close relation, F. tenax. 

 Other differences will be noticed on comparison. 



Position and locality: Chester group, Chester, 111., and Crit- 

 tenden Co., Ky. 



FENESTELLA DELICATTJLA Ulrich. 



PI. LTI.Fig.2. 



Zoarium a very delicate, rapidly expanding, foliar expansion, 

 not known to exceed 2 cm. in diameter. Branches very slender, 

 about five in 5 mm., scarcely 0.3 mm. in width; strongly convex 

 and finely granulose on the reverse, and ridge like on the ob- 

 verse. Dissepiments long and very slender. Fenestrules sub- 

 quadrangular, about 1.5 by 0.7 mm., and six or seven in 1 cm. 

 Carina comparatively strong, rounded, with an occasional very 

 small node. Zooecia in two alternating ranges, about sixteen in 

 5 mm. Apertures circular, small, and widely separated; five or 

 six to the fenestrule; peristomes prominent, especially upon the 

 outer side where they encroach upon the fenestrules. 



