510 A POPULAR EXPOSIYION OF THE 
6. Syringopora tubiporoides, Fig. 77.—The cor- 
allum in this form consists of round, elongated, and 
somewhat flexuous tubes, connected by tranverse 
tubes of short length. Another species, S. Hisin- 
geri, resembles this, but. its tubes are of much 
smaller diameter. Both occur in the Devonian 
recks of Western Canada. 
7. Columnaria alveolata, Fig. 78.—This species much resembles 
Favosites Gothlandica, the corallum being made 
up of hexagonal and polygonal cells in close 
juxtaposition, but the mouths of the cell-tubes 
are bordesed by short radiating lamelle. Nu- 
merous diaphragms are also present, but the 
see Part V.)° 
cell-walls have no pores. Trenton group (Lower 
Silurian), and principally met with at the lower 
part of this group (= Black River limestone, 
8. Petrata cornicula (= Streptelasma of Hall) Fig. 79. Corallum 
horn-shaped, simple, consisting of one large cell with 
well-developed radiating lamelle, but without dia- 
phragms. Trenton Group (Lower Silurian). A 
closely related species from the Niagara Group (Upper 
Silurian) has been named P. calicula. Another 
species, P. profunda, from the base of the Trenton 
Group, has a conical and nearly straight form. All 
of these vary in length from about half an inch to an 
inch ‘and three-fourths. 
ANY FAA 
QZ 
9. Zaphrentis prolifica, Fig. 80.—Corallum, horn-shaped, simple; 
with alternating largeand small radiating lamelle, 
and transverse diaphragms. A “septal fossette ”’ 
or indentation passes down the interior of the 
cup on one side; and externally, the corallnm 
is enveloped in a thin epitheca. This is a 
comparatively large species, varying in length 
from about an inch and a half to over five inches ; 
but a still larger species, Z. gigantea, is often 
found accompanying it. This latter form i§ 
two or three inches in diameter, and two feet 
