17 
men, a metatype (M.M.K. 436), Plate IV, figure 3. He has also examined 
the specimen and thin sections of “ Sarcinula organum Lamarck ” identi- 
fied by Etheridge (B.M. R4920), Plate IV, figures la, b. These three 
are identical. But they show exactly the same structure as C. canadensis 
var. anticostiensis and differ only in that they are giant forms. Troedsson 
(1928, 127) gives the diameter of corallites as 4 to 6 mm., but some are 
l^s than that; in R4920 they vary from 3-0 to 4-0 mm. Although their 
tabulae are less regular than in the type of C. anticostiensis they are no less 
so than in some of the Anticosti specimens. There are ten of these tabulae 
in twice the diameter of the corallite — the same number as in a few of the 
Anticosti examples. As in var. anticostiensis, the coenenchyme varies 
within one corallum from a fairly simple arrangement to a less regular one 
where the upturned ends between diaphragms assume more importance. In 
forma arctica this is especially the case in areas between the costae, wdiere 
they appear on a longitudinal section as more or less regular circles. This is 
seen to a less extent in some of the Akpatok examples of var. anticostiensis; 
and it is not altogether absent in the type itself. 
In the specimens here called forma arctica, the short, incomplete tabulae 
upturned at the periphery of the corallites are more numerous and regularly 
developed than is the case in var. anticostiensis; but this variation is prob- 
ably a direct result of an increase in size. 
The type nf C. arctica came from the Cape Calhoun beds of north- 
west Greenland. There it is apparently common (Troedsson 1928, 129). 
Etheridge’s specimen was collected from cape Hilgard, Ellesmere island. 
Their horizon is discussed on a later page, where it is suggested that the 
Cape Hilgard locality is probably of Richmond age as well as the Cape 
Calhoun beds. 
These specimens can be regarded as no more than a form of var. 
anticostiensis from which they differ only in size. It is convenient rather 
than essential that they should have a name, because their form seems 
to be restricted to the north Arctic region and is easily recognized externally. 
Following the conventions their relation to the other forms of Calapoecia 
can only be expressed as C. canadensis var. anticostiensis forma arctica. 
This may be cumbersome, but, as shown above, they are only a local race 
of the variety anticostiensis ; a shorter name would suggest that the form 
had a more complete individuality than is the case. 
With regard to their distribution: cape Calhoun is about 85 miles 
northeast of cape Hilgard (79® 4T north), which is west of cape Louis 
Napoleon, Ellesmere island. C. arctica is found at both of these localities. 
But only 35 miles southwest of cape Hilgard, on Norman Lockyer island, 
typical var. anticostiensis occurs. Thus, within a very small area a 
race of large-sized forms seems to have been developed from var. anti- 
costiensis. Further collection may show, however, that it was not even a 
race, but merely that some individuals of var. anticostiensis were favoured 
with large size. It is possible that some of Whitfield’s (19(X)) C. borealis 
may be of this form. They were collected from cape Harrison, Princess 
Marie bay, Ellesmere island, not far from cape Hilgard. Unfortunately 
Whitfield gives no scale for his figures. His species will be more fully 
considered presently. 
