No. i.] MORPHOLOGY OF THE ACTINOZOA. l6l 



The term Protactiniae, employed in the scheme, denotes an 

 order consisting of forms with twelve primary mesenteries ; with 

 one, or a pair or two pairs of secondary mesenteries on each 

 side of the sagittal axis, the increase in number of the secondary 

 mesenteries occurring from the dorsal towards the ventral side. 



The order includes Scytophorus, Gonactinia, and Oractis. It 

 seems more convenient to associate these forms in a single order 

 than to form a separate order for each one. 



Clark University, Worcester, Mass., 

 February 21, 1891. 



