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Notes on the Qicology of Cirratulus (Audouinia) 
tentaculatus (Montagu). 
By 
F. W. Flattely, 
University College of Wales, Aberystwyth. 
With Figures 1 to 7 in the Text. 
Cirratulus tentaculatus is found inhabiting the wet, sandy, somewhat 
foul mud of the Aberystwyth shore, chiefly in the Laminarian zone, 
although it also occurs in rock pools higher up the shore in which there 
is sufficient depth of sand containing the necessary organic matter. 
The presence of the worm in its natural habitat is indicated by a group 
of delicate, elongate, rosy or yellow coloured filaments of tentacular 
appearance which protrude from the sand into the pools left by the 
receding tide. These filaments nearly always display a certain amount 
of movement, either waving gently from side to side or curling slightly 
from the tips. The amount of motion and also the colour of the filaments 
will depend on the degree of freshness of the water in the pool, and this, 
of course, will, in its turn, be related to the state of the tide. 
Specimens are not easy to collect owing to the marked propensity the 
animal exhibits for lying with its body beneath stones or pieces of rock 
embedded in the mud. In rock pools or crevices where there is but little 
depth of sand and the animal lies with its body more or less parallel to the 
surface collection is almost impossible. This response to stimuli of contact 
and pressure, or, as M. Georges Bohn has it, this “ thygmotactism,” 1s very 
marked, and, in the aquarium, when specimens are placed in a vessel con- 
taining sand and a few stones, the animals will roam about till some por- 
tion, at any rate, of their bodies is undergoing pressure from those stones. 
Thus, in addition to the occurrence of sandy mud of rich organic content, 
the worm would seem to require the presence of a certain amount of rock 
or loose stones. Both these requirements are well met on the portion of 
the Aberystwyth shore opposite the College. Here a large reef of rock runs 
out to sea in such a manner as to form a barrier to the prevailing wind and 
thus to aid in the deposition of organic matter, of which no doubt a certain 
proportion is contributed by the Harbour sewer lying to southward, 
decaying fragments of alge, ete. 
