118 SYNOPTIC COLLECTION. 



A related genus, Clavularia crassa M. & K. (PI. 163, 

 fig. 2), is a simple colony with retractile zoons. It has 

 spicules but no horny sheath. In Clavularia viridis Q. 

 & G., the first zoons spring from the basal stolon, but 

 higher up they are united by simple tubes from which 

 other zoons are budded (see PI. 164, fig. i, showing the 

 skeleton of a zoon that has budded from the connecting 

 tube). The grooves on the surface of the skeleton mark 

 the position of the eight mesenteries within. The skel- 

 eton consists of a coriaceous substance with a few 

 scattered spicules, and is without openings, therefore 

 imperforate. 



Clavularia glauca Hickson 1 ( = Anthelia glauca Savig.) 

 (No. 165) puts out a fleshy membrane, the coenosarc, from 

 the bases of the zoons ; this fleshy floor is provided with 

 nutritive canals and secretes the limy coenenchyma. 



The organ-pipe coral, Tubipora hemprichi Ehr. (No. 

 1 66), when young has a long, tubular, fleshy body with 

 the mouth in the middle of the oral disc surrounded by 

 eight tentacles. The latter are fringed with small papil- 

 lae, each one of which has a tiny opening at the end. 

 The basal portion of the body sends out a fleshy layer 

 which extends over the surface of the rock and from 

 which other zoons are budded. As the colony increases 

 in size this flat lamella ceases to grow and its work of 

 giving origin to new zoons is at an end. Around the oral 

 end of the body there spreads out a rim (No. 166). This 

 may surround neighboring tubes or fuse with adjacent 

 rims, thereby forming horizontal platforms from which 

 other zoons arise. 



The spicules first appear singly in the mesoderm of the 

 base and walls of the tubes and of the cross platforms, 

 but during the growth of the animals they become united 

 by the serrations of their edges to form a solid skeleton 

 (N"o. 167). The sutures between the spicules can be 



1 See Trans. Zool. Soc. London, XIII, 1892, p. 333. 



