ORDER ACTINOIDEA. 67 
awhile, an adult, and continues the mode of propagation, until lines 
of polyps are formed; and these coalesce at intervals, and form a 
network. ‘The creeping-shoot, in many species, continues growing 
indefinitely, and sending up buds at intervals, as in fig. 26. 
It is plain, that if the buds passing out from the different sides of 
the base of each polyp should all coalesce by lateral extension, we 
should have an incrusting plate instead of a simple thread network. 
And, moreover, when these animals coalesce also by their sides above, 
as often takes place, the plate would have a thickness equal to the 
height of a polyp. ‘These different varieties are all well illustrated 
among the Zoanthide, and the last is exemplified in the Palythoa, 
described in § 30. 
66. The same process is also illustrated in the following figure of a 
Gemmipora, in which the budding is lateral from near the base of 
the polyps. ‘The buds open at the margin of the growing plate, and 
each young animal may be traced within to the preceding, as is 
indicated by the lines of the cells on the broken edge forming the 
Fig. 27. 
front of the figure. Other instances are found in the genus Mano- 
pora. Such forms have been called ezplanate or foliaceous. 
67. Very different forms result when the buds 
are not confined toa single side of the parent, as 
in the Gemmipora, just described. In the Ocu- 
line, they pass out obliquely from different sides ; 
each one gives out a bud, and that another, and so 
on successively, somewhat like the budding of the 
Sertularide (§ 16); and the zoophyte, proceeding 
from the process, is an erect or ascending stem, as 
in the annexed figures of the coralla of two species 
of this genus. Hach bud is for a time at the apex, 
but it gradually becomes lateral and then gives off Cones 
another bud from its upper side. ‘Thus bud follows bud, and the 
stem slowly lengthens. In these corals there is often a distinct spiral 
