126 SYNOPTIC COLLECTION. 



Small canals radiate from the cavities of the zoons and 

 open into the longitudinal canals around the axis. 



The fan coral, Rhipidogorgia. (No. 188) is another 

 upright coral, the branches of which unite to form a net- 

 work. The zoons are arranged on either side of the 

 intersecting branches. The yellow flesh is stiffened by 

 spicules of different shapes and the axis (No. 189) is 

 horny. 



ANTHOZOA. 

 ZOANTHARIA. 



Coming to the present day we find among living 

 Zoantharia the fleshy Actiniae which never make a skele- 

 ton. The researches of Boveri, 1 McMurrich, 2 and others 

 make it very probable that all the Actinian types have 

 descended directly or indirectly from the Edwardsiae. 



Edwardsiae. Edwardsia claparedi Pane. (PI. 190, 

 figs, i, 2) is a single form with eight simple tentacles. 

 Its body cavity is divided into chambers by eight bilateral 

 mesenteries (fig. 2). These Actiniae have the dorsal 

 and ventral differentiation of the body well marked, so 

 that a bilateral arrangement of the parts is the predomi- 

 nating characteristic (fig. 2). When young, Edwardsia 

 is free-swimming, but later it becomes stationary by 

 burying the posterior part of its body in sand. A related 

 form, Cerianthus membranaceus (No. 191) has a similar 

 habit. 



Antipathes subpinnata (No. 192) represents the Anti- 

 pathariae. -Nothing has been done as yet with the embryo- 

 logical development of this group. The young Antipathes 

 is a single, fleshy animal. At one end is the mouth with 



'Zeitschr. f. wiss. Zool., XLIX, 1889, p. 492. 



2 Journ. of Morph., IV, V, 1 890^9 1 ; Proc. U. S. Nat. Mus., 

 XVI, 1893. 



