458 



:^lEMOIKS OF THE NATIONAL ACADEMY OF SCIENCES. 



the polyp to the other, the aspect viuying, however, in ditl'erent species. In Sidetyistrxa, 

 Solendstrse.a, Favia, and Astmiigia the succession is from the dorsal to the ventral side, in buds 

 of CJadocc/ra from the ventral to the dorsal. The exceptional succession in the latter may be 

 in some way dependent upon the more rapid growth which tiikes place on the abaxial side of 

 the buds, as compared with the axial. Before it can Ije regarded as actually characteristic 



IT TE 



B 



Fig. 7. 



Vladocina arbusnda.—FoxiT diagrammatic figures illustrating the order of appearance of the mesenteries In bud polyps (r/. Pis. VI-VIII). 



(In b the lower bilateral pair marked V, V, should have I)een lettered VI, VI.) 



of the species, it will be necessary to follow the sequence in polyps reared directly from larvfe, 

 as in the case of Siderustrs'a. Until such is carried out, it may be taken as a general rule that 

 the development of the second order of mesenteries is from the dorsal to the ventral aspect 

 of the i^olyp; that is, from the anterior to the posterior border. 



