[13] ALBATROSS EXPLORATIONS. 515 
is Actinostola callosa V. (fig. 24), which often becomes 5 or 6 inches across 
the body, and is usually somewhat higher than broad. It has a large 
number of short, thick tentacles, usually deep orange in color, while the 
body is lighter, varying to salmon or pale flesh-color, and has a smooth 
leathery texture and warty surface. This and the two preceding, 
when living on the deep-water muddy bottoms, have the habit of firmly 
inclosing a large ball of mud, often 2 or 3 inches in diameter, in 
the base. This is done by the basal disk first spreading out and then 
descending into the mud, when its edges contract so as to produce a 
hollow bulb, often with only a small central opening below. This bulb 
serves aS an anchorage in the mud, but it is probable that all these 
speeies, at first, when very young, adhere to bits of corals, worm-tubes, 
shells, or some other solid substance, by a flat base, as usual with 
Actinians in shallow water, and that the base gradually becomes bulbous 
when it grows beyond its small support, for we often find young speci- 
mens thus attached, and have observed the bulb in all stages of forma- 
tion. In some cases one half the base would be flat, and adherent toa 
shell, while the other half would have the bulbous form, inclosing mud. 
Moreover, when these same species inhabit hard bottoms, covered with 
shells and stones, as often happens, large specimens occur broadly 
attached by their flat bases, so that this must be regarded as a special 
adaptation suited to the peculiar conditions of muddy bottoms, but not 
yet become a permanent character of the genera, nor even of the spe- 
cies, so far as we have been able to discover. 
Within the hollow bulbs, mixed with the mud, or next to the base 
itself, we usually find a number of chitinous pelicles, which have been 
secreted by the basal disk and cast off from time to time. This is not 
confined to either of the several genera that have bulbous bases, but is 
common to all. It indicates that the same ball of mud, or portions of it, 
at least, must be retained for a long period, or perhaps through life, 
for it is probable that individuals thus anchored in the mud do not 
move about at all, but ever afterwards remain fixed. Indeed, I have 
good evidence that some large individuals of A. nodosa attached to 
stones and shells:remain fixed in the same place for years, without any 
disposition to creep about, and perhaps they may lose this power, more 
or less, as they grow old, though they certainly have it while young, as 
do most shallow-water species. The formation of the basal bulb in 
these Actinians, and in the Alcyonium above mentioned, throws much 
light on the probable origin of the specialized muscular basal bulb of 
the Pemnatulacea. 
A remarkable new genus (Gondul mirabilis) has been recently de- 
scribed by Koren and Danielssen,* which is attached by an adherent 
base, as in Alcyonium, but has the polyps arranged on bilateral ‘ob-- 
lique ridges, as in many Pennatulacea, and with four axial tubes, 
* Bergen’s Museum, Nye Alcyonider, Gorgonider og Pennatulider til Norges Fauna, 
p. 19, pl. 10, 1883. 
