DEVELOPMENT OF PALEOZOIC CORALS 67 
is incomplete and in the latter complete. They have, however, scarcely 
any characteristics in common with the corals above considered. In 
Laccophyllum the wall is very massive and much thicker than the 
septa, and in both it is conical in shape, decreasing in diameter toward 
the tip of the corallite. This feature is reversed in the Craspedophyl- 
lum type, as in the latter the inner wall becomes smaller in diameter 
as the corallite develops. They are good examples of individuals in 
remote parallel series. 
Carinae.—The carinae are not present at the early stage repre- 
sented in Fig. 1, but the first series is well indicated in Fig. 2. ‘These 
are formed by bar-like growths ex- 
tending upward and inward in an 
arching manner (Fig. 6), and on cor- 
responding sides of the septum. In 
transverse sections they appear as 
short cross-bars through the septum 
(Figs. 2,5, 7). The mode of growth 
and the order of appearance of the 
carinae will be understood from the 
diagrammatic section, Fig. 8. The 
difficulty of obtaining a complete 
longitudinal section of a septum from 
a specimen is apparent as these seldom 
if ever develop in a true plane. The 1. 8.—A longitudinal dia- 
diagrammatic section is therefore based omen oe ee 
with ideal development of the 
upon the development of the carinae carinz. 
at different. stages as they are revealed 
by several longitudinal sections. A general idea is, however, obtained 
from Fig. 6, where the carinae are revealed in several places. In 
Fig. 8 it is seen that the tip of the corallite contains no carinae and 
this would therefore, represent a stage of Fig. 1, or earlier. ‘The first 
carina appears at the outer wall and grows upward and inward until 
it finally fades away in the region of the inner wall. As soon as the 
room is sufficiently large between the first carina and the outer 
wall, the second carina begins and takes a path similar to the first. 
A similar direction is taken by each successive carina; all terminating 
in a like manner, and new ones take their places at the outer wall. 
