BROWN, RUGOSE CORALS 
71 
taneously but come in in the same order as the secondary septa. The first 
one in each counter quadrant appears long in advance of any of the others, 
and when the others do appear, they follow the same sequence as the second¬ 
ary septa. They develop more rapidly in the counter quadrants than in the 
cardinal, four having appeared in the former when there are only two in the 
latter. 
This species agrees with Enterolasma strictum of the lower Devonic beds 
in that the tertiary septa are united with the secondary septa at their inner 
margins and do not project 
as free ridges as is the case 
with the tertiary septa in 
geologically earlier species. 
The additional figures are 
enlarged from the actual sec¬ 
tions sawed from individual 
corallites. Figure 17 (a-e), 
from a comparatively small 
individual, shows five sections. 
In figure 17a there are only 
two pairs of secondary septa 
in>the counter quadrants in 
addition to the four primary 
septa. The other four sec¬ 
tions show the addition of 
the remaining secondary 
septa and of the first pair of 
tertiary septa adjacent to the 
counter septum, as well as the reduction in prominence of the cardinal sep¬ 
tum and the development of the solid pseudocolumella. Figure 18 (a-g) 
shows similar stages in development and also the presence of tabulre and 
dissepiments (shown by white in the interseptal spaces). Figure 19 (a-c), 
from near the base of the calyx of another individual, shows to better ad¬ 
vantage the presence of tabulae and dissepiments. These sections show 
particularly well the reduction of the cardinal septum and development of 
the cardinal fossula. 
Heterophrentis prolifica Billings. 
1859 Zaphrentis prolifica Billings, Canadian Journal, (new series), vol. IV, 
p. 121, figs. 22, 23. 
1874 Zaphrentis prolifica Nicholson, Rept. on Pal. of Prov. of Ontario, pi. 3, 
figs. 2, 2a. 
