INTRODUCTION. 
XV 
irritability. The tips of the tentacles are bristled with the 
minute points, called by Dr. T. S. Wright palpocils,* 
which he considers as delicate tactile organs. These are 
specially conspicuous on the globose heads of the tentacles 
of Corynactis and Caryophyllia. I am not sure Avhether 
I ought to regard, as an organ of taste, the surface of the 
lower part of the stomach, which in T. crassicornis I find 
covered with innumerable papillas, not quite uniform in size 
or shape, some being more pointed, others more round, and 
averaging about 0003 inch in diameter. 
4. Digestive System. This is very simple, consisting 
essentially of a short tube descending from the centre of 
the disk, with an open extremity hanging loose in the 
body-cavity (Plate XI. fig. 1, c). I have already observed 
that the inner edges of the septa are inserted into its outer 
wall, and these maintain it in place, while by their trans- 
verse contraction they can draw asunder its surfaces, and 
by their longitudinal contraction they can either lengthen 
or shorten it. The stomach-wall itself, however, is muscular ; 
possessing at least the layer of transverse fibres, though I 
have not quite satisfied myself of the presence of the longi- 
tudinal layer. 
The form of the stomach is not that of a cylinder, but of 
a flattened sac, or of a pillow-case unsewed at both ends. 
This form may be well seen in pellucid specimens of A. 
dianthus, and in the smaller iLYANTHiDiE, and it may be 
examined by dissection in others. The excessive contrac- 
tion of the parts, and the copious excretion of mucus, do, 
however, present great obstacles to satisfactory demonstra- 
tions under the scalpel. I have therefore resorted to 
accessory means. A specimen of 71 crassicornis fully 
expanded I treated with laudanum, drop by drop. It 
immediately expelled the water contained in the tentacles, 
causing these organs to shrink and shrivel, but not re- 
tracting them. The mouth, which had been pursed together, 
began slowly to open, and dilated greatly, almost to the 
concealment of the tentacles, the summit of the now 
flattened animal being almost wholly occupied by the 
gaping orifice. An excellent opportunity was thus afforded 
for examining the structure of the stomach, which was 
revealed without the excretion of mucus. The languor, 
too, induced by the narcotic, allowed the parts to be freely 
See Edin. New Phil. Jouru., April, 1857. 
