No. 1.] ACTINIARIA OF THE BAHAMAS. 43 
is exceedingly difficult to detach it without injury, and when 
irritated secretes an enormous amount of mucus, its separation 
from the rock being thereby rendered more difficult. In color 
(Pl. I., Fig. 9) the column is of a brownish purple, frequently 
with a more or less greenish tinge; the disc is similar in color, 
with green bands radiating from the raised peristome towards 
the margin; the peripheral tentacles are pale bluish green, with 
brown tips, the disc tentacles being seal-brown or a somewhat 
lighter shade of the same color; the mouth and cesophagus are 
white. 
This form is known from St. Thomas, where it was originally 
discovered. Some of the specimens obtained at New Provi- 
dence are sufficiently light colored as to agree fairly well with 
the description given by Duchassaing and Michelotti of the 
St. Thomas examples. 
The column measures about 1.6 cm. in height, and is smooth. 
It expands considerably above, the margin being frequently, in 
full expansion, folded back so as to conceal the column. No 
special sphincter muscle is present, and in fact the circular mus- 
cles of the column are throughout exceeding feebly developed, 
a fact which agrees with the small power of infolding the disc 
which these forms possess ; in a single instance only did I meet 
with an individual which had this power. The ectoderm of the 
column is thrown into longitudinal series of minute elevations, 
each series corresponding with an interval between two mesen- 
teries, and the elevations being formed by delicate processes of 
the rather thin mesogloea (0.85 uw). So far as could be ascer- 
tained there is a complete absence of cnidoblasts in the ecto- 
derm, the only cells present being apparently glandular, the 
contents of which do not stain, sections through the column 
wall having thus a very characteristic appearance. The endo- 
derm also contains gland cells, and is richly packed with “ yellow 
cells:” 
The margin is occupied by the single row of peripheral ten- 
tacles, which are short, cylindrical, and abruptly acuminate. 
They vary somewhat in size, a small one usually alternating 
with a larger one, though frequently two or three small ones 
will intervene between two succeeding large ones. The num- 
ber of these tentacles varies; in larger specimens they are 
somewhere in the neighborhood of 150. 
