CORALS AND BRYOZOA. 
217 
Fistulipora unilinea, n. sp. 
PLATE LVII, FIGS. 1, 2, 5. 
Zoarium sometimes consisting of thin lamellate expansions, incrusting Cyatho- 
* 
phylloid corals or other objects, but very frequently forming hemispherical 
or spheroidal masses by the superimposition of successive layers of growth. 
Cells tubular, cylindrical, rectangular to the surface ; septa wanting. Inter¬ 
cellular space vesiculose, vesicles near the base large, irregularly disposed, 
more regularly superimposed above, but never having the appearance of 
septate tubuli. When the vesicles are regularly superimposed there 
are about forty in the space of 5 mm. Cell apertures circular, diameter 
.33 mm., very closely and irregularly disposed; on different fronds and 
under different conditions they vary greatly in apjiearance; usually the 
peristomes are thin, equally elevated, and the apertures surrounded by one 
series of mesopores; on other fronds the peristomes are more decidedly 
elevated and the apertures are a little more distant. Sometimes there is an 
oblique projection or slight denticulation on the posterior portion of the 
peristome; at other times, on portions of a frond, the peristomes are thick¬ 
ened, coalescing with those of adjacent apertures, obliterating the mesopores, 
which in this condition resemble the polygonal cell apertures of a Ch^tetes. 
When the frond is well preserved there are frequent spinules on the peri¬ 
stomes. Mesopores minute, usually only one series between adjacent aper¬ 
tures; margins elevated a little less than the peristomes, granulose, the 
granules very frequently obscuring the mesopores. Surface marked by very 
slightly elevated monticules, the centers of which are usually distant about 
6 or 7 mm., with a space 1.50 or 2 mm. in diameter, destitute of cell aper¬ 
tures and occupied only by mesopores, which are obscured by the prominent 
granules on their margins ; the adjacent cell apertures radiate from the sterile 
areas and are larger than the others, having a diameter of .50 mm. 
This species most nearly resembles F. spheroidea, but may be distinguished by 
the smaller cell apertures, the granulae on the margins of the mesopores, and 
the presence of monticules: from F. constrida it is distinguished by the some- 
