Bl. Si cocdeniasasbila place by salina. 
tioned in $ 17, a that from internal lamelle, which char- 
acterises the Actinoidea 
Ova.—The ova pa from the sides either singly or in clus- 
ters; and the clusters are naked as in figure 1, 10, or enclosed, in 
membranous cases or vesicles. The fsbiie 5, 6, 6d, 7, and 8, 
: Fig. 7. Ta Fig. 8. 
Plomularia. Sertularia, 
| ieditesent some of these ova-bearing vesicles. ‘They gradually 
‘develop from the side of a branch, or at times from a creeping 
-- Yoot-like shoot, which grows watward like the creeper of a plant, 
‘sending up its bade and flowers at intervals (fig. 8). They some- 
times may be shown to be the production of particular polyps in 
a cluster, and in other cases individuality seems to be lost and 
they belong rather to the group as a whole. The ova are easily 
distinguished arranged along an axis, or on one side of the vesicle, 
and Lister has shown that they communicate through this main 
axis with the trunk of the zoophyte and the fluids vibrate into 
‘them. Dr. Charles Pickering, an associate in the Exploring Ex- 
: pedition, pointed out to me in 1838 the close analogy which sub- 
sists between the structure of a vesicle with its included ova, 
and a branchlet of the zoophyte. This singular point has been 
thoroughly investigated by E. Forbes, Esg., and the fact of this 
arrangement fully ascertained.* The above figure (fig. 7) is a 
_ good example of the fact; it is by Dr. Pickering and was drawn 
from the specimen on which the observation was made. ‘The 
vesicle to the right contains evidently i in its structure all the ele- 
ments of the central pmnate frond, and appears as if made by 
folding together the branchlets from either side of the midrib, 
' these branchlets.and traces of the eatioles being distinct over the 
surface of the vesicle. 
. cee Brit. Assoc. for 1844, p. 94. 
