ON THE OCCURRENCE OF THE GENUS COLUMN ARIA — ETHERIDGE. 3 1 
for about one-third of their diameter, or perhaps a little more, whilst 
the latter are mere marginal crenulations. These primary septa 
are tapering and spike-like in cross-section, although at the same 
time true lamellse, extending from top to bottom of the corallites. 
There is not the faintest trace of any meeting of the septa in the 
cal ice centres to form a spurious columella as described in C. rigida , 
Billings.* At first sight the corallites appear to be provided with 
very few septa in consequence of the small size of the secondary, 
and even these are set far apart. Furthermore, the septa do not 
spring sharply from the corallite walls, but in consequence of the 
inner edges of the latter being concave between them, a more or 
less festoon-like appearance is given to the cross-section of each 
corallite, somewhat as one sees in the genus Heliolites . These 
appearances at first caused doubt to arise in my mind as to the 
propriety of referring this coral to Golumnaria , but on referring 
to Prof. Alleyne Nicholson’s excellent figures,! I found that in both 
C. alveolata and C. calicina very much the same features existed. 
The stereoplasm ic thickening of the septa is unequal, some 
being thin and spike-like ; others, from a greater preponderance 
of this deposit, becoming club-shaped (PI. viii., Fig. 6). Tn some 
corallites the secondary septa become scarcely, if at all developed, 
in others they assume the character previously described. 
In no instance have 1 noticed an undue predominance in length 
of one or more septa, a point in which C. pauciseptata differs from 
C . calicina at least, but there is certainly no regular development 
of four septa as in Stauria , nor the slightest trace of a division 
into cycles. Many of the corallites are partially infilled with a 
dendritic growth of iron oxide fringing the septa. 
On longitudinal weathered surfaces, the primary septa appear 
as strong continuous lamella), their paucity and larger comparative 
size rendering them conspicuous objects. 
The tabula) (PI. viii., Fig. 7) are particularly well developed, 
simple, complete, mostly horizontal, very seldom thickened, opposite 
in contiguous tubes, or very slightly alternating, in other words 
sub-opposite. They vary from three-quarters to one millimetre 
apart, and in a few rare instances are somewhat more distant from 
one another. The non-horizontal are simply bent or curved in 
some portion of their course, never vesicular or incomplete. The 
diaphragm forming the floor of the calice is striated by the septa 
passing on to it. 1 he intertabularor old visceral chambers are nearly 
square, from the fact of the transverse measurements of the tubes 
and the distance apart of the tabula) being so nearly coincident. 
There is not the slightest trace of the existence of the mural 
pores, or intramural canals, so characteristic of the Favositida). 
* Teste Nicholson, loc. cit., p. 196. 
f Loc. cit., t. 10, f. 1 and 2. 
