CORALS AND BRYOZOA. 
263 
regularly disposed in parallel longitudinal rows, eight rows on each face of 
the branch ; the apertures of the marginal rows are larger than the others, 
having a length of .30 mm., and are oblique to the axis of the branch. 
Peristomes thin, slightly and equally elevated, not denticulated, and when 
well preserved granulose. Between adjacent cell apertures, in a longitudinal 
direction, are two minute pits, arranged laterally, partitions very slightly 
elevated; in the course of growth these pits form minute tubuli between 
the cell tubes. The peristomes are laterally wholly or partially in contact, 
according as the apertures are opposite or alternate, and coalesce, giving to 
the ranges of apertures the appearance of being separated by comparatively 
prominent granulose ridges. 
—AA- -it- 
'7V' -7v- -Tf- 'A' -TV* ■7V' 'A' 'TV* •7V* 
Formation and locality. Hamilton group, West Williams, Ontario, Canada. 
TiENIOPORA, Nicholson. 1874. 
TiENIOPORA EXIGUA. 
PLATE LXIX, FIGS. 15-26. 
Toeniopara exigua, NrcuoLSOx. Palaeontology of Ontario, p. 10S. 1874. 
“ “ Hall. Trans. Albany Institute, vol. x, p. 192. 1881. 
Pteropora duogeneris, Hall. Trans. Albany Institute, vol. x, p. 192. 1881. 
ToBniopora exigua, Hall. Report of State Geologist for 1883, p. 49. 1884. 
Zoarium ramose, flattened, proceeding from a spreading base, or from rootlets 
attached to foreign bodies; branches triangular or flattened. The branches 
of the lower portion of the frond are usually triangular, although this condi¬ 
tion may occur on all portions of the frond, sides concave, equal or nearly so, 
width 3 mm. or a little more; from each angle proceed depressed quadran¬ 
gular branches, which both bifurcate and ramify laterally, continuing growth 
in the same manner as the parent branches; the flattened branches are 
from a little less than 3 mm. to 4 mm. wide, with parallel margins, not 
expanding before bifurcation; non-celluliferous marginal space flat, smooth, 
width from .33 to .50 mm.; transverse section rhomboidal, sometimes 
abruptly contracted near the margin, angular at the middle, with a prominent 
