SUBDIVISIONS OF ACTINOID POLYPS. 6] 
The tribes adopted are those recognized by Prof. Vegrill, 
and have the limits he has assigned tothem. The classification 
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 21. Some 
of the figures of corals on former pages are here repeated in 
order to present together those of like relations. 
1. Species without internal Coral Secretions. AcrinarRia of 
Verrill. 
1. The Actinza tribe, or ActTINACEA, secrete no coral inter- 
nally, and moreover have a muscular base, with some degree 
of locomotion by means of it. The Actinie of the frontis- 
piece, and of pages 23, 24, 26, are examples. 
2. The Zoanthus tribe, or Zoantuacea. The species here 
included are like the Actiniz in secreting nocoral. But while 
they have a base, it is not muscular, and they are never capable 
of locomotion. The polyps have a thick or somewhat leath- 
ery exterior, and, as already observed (p. 39), have gills, or 
branchiz. Some of the species are solitary polyps; but 
generally they form compound masses or zodthomes, 
by budding; sometimes making simple lines of polyps 
over a supporting surface; at other times incrusting plates, 
or irregular masses. The following figure (from Verrill) 
represents a species found in American seas off the coast of 
New Jersey, in deep water, and also in Massachusetts Bay, 
which has a habit of fixing ona shell for its support and of 
always taking one containing a soldier crab. The shell 
finally becomes dissolved away—how, it is not known, by 
