Part II,—Stichodactylinee and Zoanthee. 169 
brown ; more centripetally, it is divided into narrow, radiating areas separated by 
dark lines. Each area consists of distinct, opaque white patches, or of continuous, 
opaque white bands, and corresponds with the rows of tentacles. The central, 
naked part of the disc is darker, and usually shows a purplish tinge, and a few 
white flecks may be scattered about. The margin of the lips is a stronger purple. 
The tentacles, both in different regions of the disc, and even in different parts of 
the same tentacle, also vary considerably. At their origin the short stems are of 
much the same colour as the portion of the dise from which they arise. Many of 
the inner show an opaque white circle at the place of origin. The tips of most are 
strongly coloured ; at their thickest part is an opaque white annulus, while the 
area immediately above may be greyish, yellowish-brown, or iridescent green. 
The last-mentioned condition is usually exhibited by the peripheral cycles, and 
the first cycle of this series often projects slightly beyond the others, its tentacles 
having intensely opaque white tips, which give a marked peculiarity to the colour- 
pattern of the disc. Usually the tips of the internal tentacles are whiter than those 
of the outer. At any part of the tentacular area, larger, bright green tentacles 
may occur. 
The capitula of all the tentacles of several specimens obtained near the bathing 
place at Port Antonio were a bright-green, and the white opacity on the dise was 
absent, the whole surface, except the purple peristome, being a rich dark brown. 
As mentioned by Duchassaing and Michelotti, the brighter colours are 
sometimes evanescent or may undergo modification. ‘The rich, tentacular colours 
of some specimens kept in the laboratory, and exposed to the full sunlight fora few 
hours, practically disappeared, the whole dise and tentacles being reduced to a 
thin, opaque white and delicate brown. Others, especially those not so brightly 
coloured, showed no alteration. 
The diameter of the expanded disc, in the living condition, varies from 10 to 16 
cm., or may even expand to as much as 20 cm. The diameter of the column may 
be about 6 cm., but depends much upon the amount of distension; the height is 
from 7 to 8 cm., but in a tall jar in the laboratory the column elongated to as 
much as 9 or 10 cm., and swayed to and fro. The length of the tentacles 
is 0-4 cm., and the greatest diameter, which is towards the tips, is 0°2 cm. The 
disc of specimens preserved in formol is about 5°5 cm. in diameter, and the 
column about 3°5 cm. in height, and the same in diameter. 
ANATOMY AND HiIstToLoeGy. 
The basal ectoderm is a broad layer, constituted mostly of supporting 
cells, among which are a few granular gland cells. ‘The mesogloea is usually 
narrower than the ectoderm, and is finely fibrous in character, with 
