34 ZOOPHYTES. 
Fig. 13 6. The coats of the stomach, in this species, contain the 
a 
\ F,4 / same minute spicules as the tentacles; and, in the general 
ar 0 intezuments of the body, they are still more abundant. 
The visceral cavity is divided vertically by numerous 
lamelle attached to its walls, the larger of which are united by their 
inner margin to the exterior of the stomach, and serve to fix it in 
its place, and at the same time to vary its shape by their muscular 
action. This structure is exhibited in the annexed cut of an ideal 
transverse section through the centre of an Ac- 
tinia. The central ring is a section of the sto- 
mach, exterior to which the radiating lamelle are 
shown of various sizes. All the lamelle, large 
and small, extend along the under surface of the 
disk to the stomach; but only certain lamelle 
at intervals retain this width and continue con- 
nected with the stomach to its lower extremity ; 
the greater part narrow at once, and are of va- 
rious widths, as in the figure annexed. Below the stomach, the 
larger lamelle also are abruptly narrowed, so as to leave here an 
open space or chamber; the lamellw afterwards extend inward again 
along the base of the polyp, and coalesce at centre, or are lost in the 
general structure of the base. The cavity or visceral chamber below 
the stomach is sometimes nearly bisected by the union of opposite 
lamelle. 
In the Actinia marginata, the lamelle, as seen through the skin, 
Fig. 15. have the arrangement in figure L5, two stouter lamellae 
| with a broader interval alternating with two thinner 
lamelle and three narrower intervals. The same fact is 
indicated by the vertical linings on the Actinia, figure 22, 
plate 3; and, from some facts hereafter to be stated, it will 
be shown to be a very common arrangement in these animals. The 
vertical markings of Actiniz, as well as the radiations of the disk, are 
all connected with the position of the fleshy lamellze within. The 
above figure also shows that these lamelle are very numerous,—szz 
or seven being included in a breadth of a quarter of an inch. They 
are not as distant as in figure 14, which is drawn for general illustra- 
tion, and is not strictly accurate. 
The number of lamelle in a certain breadth of interval is the same 
in different individuals of the same species. As a@polyp enlarges by 
growth, new lamelle form between the others, in the widening inter- 
