CORALS AND BRYOZOA. 229 



cell apertures, and the numerous spinules on the peristomes and at the angles 

 of the mesopores ; the resemblance, however, is very close, and with a compari- 

 son of more specimens it may perhaps be possible to unite the two forms : 

 from F. digitate it is distinguished by the larger and more distant cell aper- 

 tures, the more prominent peristomes, and the numerous spinules on the peri- 

 stomes and at the angles of the mesopores : from F. micropora, by the larger 

 cell apertures and more prominent peristomes, the comparatively smaller meso- 

 pores, and the numerous nodes of the peristomes and mesopores : from F. seg- 

 regata, by the somewhat smaller, more decidedly oval and more closely dis- 

 posed cell apertures, smaller mesopores, and numerous nodes of the peristomes 

 and mesopores : from F. involvens, by the larger and more decidedly oval cell 

 apertures, and the numerous nodes : from F. minuta, by its more closely dis- 

 posed cell apertures, the much smaller mesopores, and the difference in the 

 appearance of the nodes ; the cell apertures and mesopores are never so 

 arranged as to give to the surface a striated appearance, a feature which is 

 characteristic of that species. From F. mediopora of the Lower Helderberg 

 group, it is distinguished by its much smaller mesopores; and from F. parasitica, 

 by the larger cell apertures and smaller mesopores. 



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



FiSTULIPORA DIGITATA. 



PLATE LIX, FIGS. 12, 13. 



Thallostigina digitata. Hall. Trans. Albany Institute, vol. x, p. 185. 1881. 



" " " Report of State Geologist for 1883, p. 24. 1884. 



ZOAR10.M consisting of thin lamellate expansions incrusting other objects, 

 especially Cyathophylloid corals ; greatest thickness of fronds observed about 

 .50 mm. All the specimens seen present a digitate appearance. Cell ap- 

 ertures oval, length about .20 mm., width from one-half to two-thirds the 

 length, clo.sely and usually irregularly disposed, but sometimes somewhat 

 regularly arranged in diagonally intersecting rows, separated by a space 

 equal to one-half the diameter of an aperture. Peristomes very thin, 

 smooth, slightly elevated, the apertures often presenting a somewhat im- 



