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. digitata 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¬ 
regates, 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 TJX, FIGS. 12, 13. 
Thallostigma digitata, Hall. Trans. Albany Institute, vol. x, p. 1S5. 18S1. 
“ “ “ Report of State Geologist for 1883, p. 24. 1884. 
Zoarium 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, closely 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- 
