BROWN, RUGOSE CORALS 
53 
from the Black River limestone, and he has given a very good diagrammatic 
drawing of one of these individuals, showing it as if it were cut along the 
counter septum and unrolled or flattened out. I have examined the speci¬ 
mens studied by Gordon and numerous others in the paleontological collec¬ 
tions of Columbia University. They are all silicified specimens found in 
the Black River limestone at Georgian Bay, Limestone Island, from which 
the calcareous matrix has been removed by acid. Many of the specimens 
were very small and therefore very young individuals. The septa of these 
young individuals were not developed to a sufficient extent to unite in the 
middle of the calyx. As a result of this, one can see the whole structure of 
the individual and can note the development of the septa relative to one 
another and can compare their size and length. In all of these individuals, 
the tip or youngest stage of the calyx is lacking in septa. The first septa 
to appear in the base of the calyx or cup are the four primary septa; the 
cardinal, two alar and counter septa. In some of the very smallest specimens 
a millimeter or less in diameter and from one to two millimeters long there 
were no septa present, the calyx consisting only of a smooth hollow cone, 
sometimes straight and sometimes slightly curved or twisted. 
The question now arises as to what this absence of septa in the youngest 
individuals may mean. Three possible explanations are suggested: 
1. Silicification was imperfect, and the septa in the earliest stage were 
not replaced and preserved in the silicified specimen; 
2. Resorption may have taken place during the growth of the young 
individual, 2 thus leaving no septa at this stage to be preserved. 
3. In its earliest stages this coral may have had no septa, its skeleton 
consisting only of a conedike structure surrounding the polyp. 
It is hard to understand how imperfect silicification can be relied upon to 
explain the absence of septa in the youngest stages of these corals when the 
delicate edges of the septa in the later stages are uniformly well preserved. 
This condition could easily be explained by the theory of resorption of the 
earliest parts of the septa, but this is very doubtful as resorption has not 
been noted in corals, and it seems more likely that in the earliest stages no 
septa were present. A persistence into the adult stage of this embryonic or 
earliest septa-less condition might easily explain the origin of such a genus 
as Cystipkyllum, which never develops septa. 
After the four primary septa appear, secondary septa are added in all 
four quadrants. In this species the first pair of secondary septa in the 
counter quadrants and the first pair in the cardinal quadrants are apparently 
added simultaneously, whereas in the geologically later species of the Strep- 
2 See Gordon op. cit. p. 124. 
