of the Rn^josa to the living Zoanthete. 



387 



A transverse section taken towards the upper part of the same corallum 

 as before. The septa are now comparatively thinner, and wide inter- 

 septal chambers occur. The former are vet swollen and partly fused 

 at their inner e.\tremity. The chief septum is enlarsj-ed at its middle 

 e.vtremity, constituting a nearly free columella, and the counter 

 septum is greatly reduced. Compared with the previous section, 

 an additional pair of septa occurs (D), but, exc^*pting the two axial 

 septa, the difierent members are so nearly alike in size as to render 

 it impossible to determine from this source alone whether the new 

 pair has arisen within the middle or the lower syst'ms. A serial 

 section, coming somewhat earlier, but too much fractured to be 

 drawn with the camera, shows distinctly a very small septum en 

 the upper aspect of the lower pair of primary septa, and in this later 

 section I interpret them as being represented by the septa, 1), 1). 

 All the sections indicate tliat growth proceeds more rapidly within 

 the middle system than within the lower. Four bilateral pairs of 

 secondary septa now occur within the middle systems, and only two 

 bilateral pairs within the lower systems. Some variation exists in 

 the different calices with respect to the number of septa arising in 

 each system, but in most mature calices of the species four new pairs 

 of septa are developed within the middle systems and three p.tir» 

 within the lower systems. 



97* 



