6 
separated by half a diameter and circular, or crowded or hexagonal. In 
C. canadensis the corallites have a diameter of one line or more and they 
are either in contact or circular. The writer agrees with Billings that these 
two different “aspects” occur; they are apparently just an expression of 
the conditions under which the coral was growing. But he finds that, 
although two corals may differ in the diameter of their corallites to the 
extent that Billings has indicated, no difference in structure can be observed 
to accompany this variation in size. Moreover, the extent of this variation 
can be observed in a single corallum, or two coralla from the same horizon. 
Foerste (1916, 295) states that “ The Black River specimens of Calapoecia 
appear to have thinner corallite walls, the arrangement of the pores along 
horizontal lines appear more conspicuous, and the denticulation along the 
septal ridges appears more conspicuous, but Lambe is probably correct in 
failing to find any constant difference, of sufficient importance to be 
regarded as specific, between the Richmond and Black River forms.” And 
again in 1929 (144) “ at any rate, Calapoecia is very rare in the Black River 
formation, the colonies are very small, the corallites are relatively small, 
and such specimens as I have collected myself and saw in the collection 
in the Geological Survey of Canada appeared to me distinguishable from 
those in the Richmond, though I might change my mind on making a 
detailed study of the series.” The present wTiter has found considerable 
variation in the Richmond examples of Calapoecia canadensis or huronen- 
sis and is unable to agree with Foerste’s statement as to the difference 
between Black River and Richmond examples. Even the “ aspect ” of 
certain Richmond forms is identical with that of the Black River examples 
that have been examined. 
The result of the present study is that undoubted C. canadensis is 
seen to vary over a number of specimens so gradually in the direction of 
“ C. anticostiensis ” that these two forms cannot be regarded as separate 
species. The significance of this variation is discussed on a later page. 
Distinction between forms cannot be based on the diameter of corallites, 
as Troedsson has suggested (1928). A difference in internal structure does 
not accompany a variation in this character; nor can groups characterized 
by a distinct size of corallite be distinguished, for there is every graduation 
from the smallest to the largest size. 
But since the two extremes of this variation are easily recognizable in 
the field, it is convenient that each should be distinguished by name. This 
being so, the stage in the variation intermediate between these two, and 
which could be compared with equal truth with either one or the other 
of these extremes, should be distinguished also. It is proposed, then, to 
revise the genus Calapoecia Billings as follows: 
DIAGNOSIS OF VARIETIES OF CalapOCCia BILLINGS 
C. canadensis Billings Corallites in contact, no coenen' 
chyme. 
C. canadensis var. ungava, var Corallites both in contact and dia- 
nov. tant; with little or no coenen- 
chyme. Intermediate between the 
above and var. anticostensis. 
