SS COKALS AND CORAL ISLANDS. 



diverges from his system in uniting the non-coral making and 

 coral-making species into one grand division, that of the 

 Actinoids (on the ground of the close resemblance of the 

 polyps), and also in separating from the latter the Cyatho- 

 phylloid corals, for the reasons mentioned on page 5. Some 

 of the figures of corals on former pages are here repeated in 

 order to present together those of like relations. 



1. Species iciifhont internal Coral Secretions. Actinaria of 



Verrill. 



1. The Actinia tribe, or Actinacea, secrete no coral inter- 

 nally, and moreover have a muscular base, with some degree 

 of locomotion by means *of it. The Acdniae of the frontis- 

 piece, and of pages 6, 9, are examples. 



2. The Zoanthus tribe, or Zoanthacea. The species here 

 included are like the Actiniae in secreting no coral. But while 

 they have a base, it is not muscular, and they are never capable 

 of locomotion. The i)olyps have a thick or somewhat lea- 



El'IZOANTHL'S AM ERICA ^• US, V., WITH EirACa'KrS Pi: BESCEIsS, Sx. 



thery exterior, and, as already observed (p. 19), have gills, or 

 branchiae. Some of the species are solitary polyps ; but gener- 

 ally the>' form compound masses or zoothomes, by budding; 

 sometimes making simple lines of polyps over a supporting 

 surface ; at other times incrusting plates, or irregular masses. 

 The preceding figure (from Verrill) re])resents a species found 

 in American seas off the coast of New Jersey, in deep water, 

 and also in Massachusetts Bay, v/hich has a habit of fixing on 

 a shell for its support and of always taking one containing a 



