458 



MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



the polyp to the other, the aspect varying, however, in different species. In Siderastriva, 

 Solenastrsea, Favia, and Astrangia the succession is from the dorsal to the ventral side, in buds 

 of ( 'ladocora from the ventral to the dorsal. The exceptional succession in the latter may be 

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

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



BT "e: 



B 



Fit;. 7. 



Cladocora arbuscula. — Four 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 been lettered VI, VI.) 



"I I lie species, it will be necessary to follow the sequence in polyps reared directly from larvae, 

 as in the case of Siderastrsea. 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 polyp; that is, from the anterior to the posterior border. 



