120 C. E. Gordon — Early Stages in Paleozoic Corals. 



" One pair forms the 'alar' or lateral septa of the paleontolo- 

 gist, while the two moities of the remaining pair, recognized by 

 Ludwig and Pourtales, but not accepted by Kunth, are disposed 

 one on each side of the axial septum on the convex side of the 

 calice." 



By the several figures reproduced here, e. g., figure 5 or 

 figure 12, we observe .how accurately this statement disposes 

 of the septa, so far as their position is concerned, according to 

 the Zaphrentoid plan. We see the "two moities" occupying 

 exactly the position which the first two secondary septa to 

 appear in the counter quadrant should occupy and we see 

 them appearing before those of the cardinal quadrant as the 

 greater number of septa in the counter quadrant of the adult 



16 



Figure 16. 

 enlarged. 



-Streptelasma prqfundum. Diagrammatic drawing somewhat 



would indicate to be the natural and logical order. The fact 

 that the counter quadrant has the greater number of secondary 

 septa supports the idea of acceleration in this quadrant. It is 

 also to be noted that the number in the upper quadrant of 

 Duerden's figures exceeds that in the lower quadrant by more 

 than one, if we include the so-called "primary" septa. 



How are we to account for this close resemblance of L. pro- 

 liferum to a typical Zaphrentoid ? Are we to regard these 

 "primary" septa, which "are disposed one on each side of the 

 axial septum on the convex side of the calice," as primary or 

 secondary? If primary, what evidence is there that they are 

 primary ? If secondary, what evidence can be brought for- 

 ward in support of their secondary nature, or what explanation 

 can be offered of their appearance so early in the life history 

 of the individual ? The strongest evidence of their primary 

 nature, of course, is their presence in the extreme tip of the 



