BROWN, RUGOSE CORALS 
51 
The paleontological collections of Columbia University are particularly 
well supplied with material of the Streptelasma and Zaphrentid groups, and 
this material was placed at my disposal. The particular species studied will 
first be described in geological order, and these descriptions will be followed 
by a discussion of the principles involved. 
The study of coral morphology has been hampered and confused by 
the duplication of terms and ambiguity of expressions used in referring to 
certain parts or features of the coral structure. Among the multitude of 
names and terms used for the different parts of the coral structure, it is not 
always easy to determine which is the best or which is correct according to 
precedence of application. The following is a partial list of the terms 
used in these studies with explanations of their meanings. 
Corallite — the complete hard part or skeleton of an individual coral. 
Calyx — the cup-like upper or larger end of the corallite. 
Septum — a more or less radially placed upright thin laminar partition 
in the corallite. 
Carinoe — well-marked vertical or curving cross bars on the sides of the 
septa. 
Dissepiments — horizontal plate-like structures which bridge across 
between the septa. 
Tabulae .— well-developed dissepiments which bridge across the entire 
• calyx. 
Primary septa — the four first-formed septa which divide the corallite 
into four quadrants in which the four sets of later septa are devel¬ 
oped. They are the cardinal septum, the counter septum and the 
two alar septa. The cardinal septum is located at the ventral or 
anterior end of the median axis of the corallite, and the counter 
septum at the dorsal or posterior end. The alar septa are located 
one on either side of this median axis. 
Fossula -— a depression or furrow surrounding the cardinal septum; 
also frequently applied, though incorrectly, to the depression or 
furrow between the alar septa and the septa of the counter quad¬ 
rants. This is called pseudofossula by Grabau in his “North 
American Index Fossils.” 
Secondary septa — the later developed prominent septa which either 
reach or almost reach the center of the calyx. 
Tertiary septa — small septa arising in the interseptal spaces between 
the septa of the primary and secondary cycles. In the geologically 
earlier forms these project freely into the calyx throughout their 
length. In the later forms they are attached by their inner margin 
to the primary or secondary septum immediately dorsal to them. 
