M<)rph(iJ(i(j>j of the Madreporaria. 



237 



very satisfactory for tlio present study, liavinn^ perfect tips 

 and septa clearly disjjlayed. Four of tiie early stages are 

 reproduced in figs. 13-16. Here, again, on the earliest 

 appearance of the septa six members are present, equal in 

 size, situated at equal distances apart, and disposed approxi- 

 mately in a radial manner; the mctasepta are added at four 

 regions in the maniu'r just described, the newer as they 

 ap[K'ar bein;^ inturned towards the older. 



Fiff. 15. 



Fijr. IG. 



Figs. 13-16. — Series of sections showing four early stao-es in the .«eptal 

 development of Zaphrentis pusilla. The general relationships very 

 closely resemble those of the two series already described. 



In addition to these four very decided cases of liexamerism, 

 secured from several specimens of each species, six primary 

 septa have been demonstrated in Iladrophyllum glans (White), 

 Hadropliylluin jiauciradiatnm^ E. & H., and Microci/clus 

 discus, Meek & Worthen, though, largely on account of their 

 squat form, these species are not so well adapted for displaying 

 the entire septal development as those figured. Still other 

 rugose corals have been examined in which it has been found 

 impossible to secure the protoseptal stage alone, yet when 

 the earliest stage is reached at which septa are exposed their 



Ann. ct' }[a</. X. Ilist. Scr. 7. Vol. xviii. 17 



