510 



MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



Fig. 15/ represents the mesenterial condition obtained from a transverse section through the 

 lower part of the stomodseum of another decalcified polyp. The six protocnemic pairs are now 



n 



Favia fragvm. — Young polyp in which all the pairs of protocnemes (I) are united with the stomodamm, and the six pairs of first-cycle 



metacnernes (II) are developed. 



all complete, and six alternating pairs of metacnemes are full}' established as a second cycle. 

 The next figure, from a somewhat larger polyp, shows the commencement of the third cycle of 



HI 



HI 



2 H 



I 



Fig. 15<7. 

 JtanVi fragum. — Polyp with six pairs of second-cycle metacnemes (III). The succession is from the dorsal to the ventral aspect. 



mesenteries (fig. lor/); its development also is proceeding by isocnemic pairs in a dorso-ventral 

 or antero-posterior order. 



