CORALS AND BRYOZOA. 251 



the peristomes. Rows of apertures separated by prominent, rounded, smooth 



ridges, having twice the width of the cell apertures. 



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Formation and locality. Hamilton group, Darien Centre, N. Y. 



Stictopora subbigida. 



PLATE LX, FIG. 21. 



Stictopora subriffida. Hall. Trans. Albany Institute, vol. x, p. 190. 1881. 

 " " Rejwrt of Stat* Geolofcist for 1883, p. 43. 1884. 



ZoARiOM consisting of a flattened, dichotomously branched frond ; the base is 

 composed of several rootlets, which are attached to foreign bodies ; for a 

 short distance from the base the stipe is broadly oval, not expanding before 

 bifurcating; branches about 1.50 mm. in width, margins parallel; trans- 

 verse section lenticular, greatest thickness observed .75 mm.; non-cellu- 

 liferous marginal space narrow, margin frequently crenulated ; bifurcations 

 comparatively very distant, sometimes occurring at intervals of 15 mm. or 

 even more ; branches diverging at an angle of about sixty degrees. Cells 

 tubular, for a portion of their length nearly parallel with the mesotheca, 

 then abruptly turning and opening directly outward. Intercellular space 

 occupied by irregularly disposed vesicles. Cell apertures circular, minute, 

 diameter .10 or .12 mm., somewhat pustuliform, disposed in parallel longi- 

 tudinal rows, five or six on each face of the branch ; apertures separated 

 longitudinally by more than twice their diameter. Peristomes thin, slightly 

 and equally elevated, not denticulated on the specimens observed. Ranges 

 of apertures separated by prominent, rounded ridges, having a width greater 

 than the diameter of an aperture, and forming the most prominent feature 



of the frond. 



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Formation and localities. Hamilton group, near Middleburg, Schoharie county, 

 and railroad cutting, two and a half miles east of Alden station, Erie county, 

 N. Y. 



