325 
Balanus allium Darwin. 
Off Jolo; ab. 20 fathoms, 17/III 14. Several small specimens on a caryo- 
phyllid, some few placed on a madreporarian together with 
Pyrgoma sp. 
Subgenus Conopea (Say) Pilsbry. 
Hoek (1913) seems to think that the development of coral 
polyps in the coenosark covering the barnacle is an exception as 
is evident from the following remark under Balanus investitus: 
„This remarkable species presents us with an interesting case of 
commensalism. The cup-formed basis is attached to a part of the 
bifurcating stem of an Acanthogorgia, which is covered by a sub- 
stance composed of a tissue interwoven with calcareous spiculae 
and developing here and there into little calyces, from the surface 
of which numerous spiculae stand off. The shell of the Balanus is 
covered by the same substance which here also develops into 
numerous such calyces“. Indeed this remark suits any Conopea 
inhabiting octocorals as far as I have had an occasion to study 
them. The symbiosis of cirripeds and corals is far more common 
than one might believe from the statements in the special memoirs, 
as I have pointed out in a previous paper (1916), and especially 
do the conopea-species seem to be common in octocorals of the 
Indo-pacific regions. Nevertheless they may appear to be scarce, 
owing to their imbedding which causes them to be overlooked or 
not payed heed to by coral-investigators in common. Their fixed 
orientation as to the coral colony, their elasticity in shape accord- 
ing to the coral species, and the specific diversities of skeletonal 
development and armature of the cirri announce fields of biolog- 
ical study for investigators who are able to study the living an- 
imals. We are indeed to-day as ignorant of this symbiosis as we 
were in the days of Darwin. 
? Balanus calceolus Darwin. 
Off Jolo; ab. 12 fathoms, 17/III 14. Five specimens imbedded in a gor- 
gonarian. 
The specimens agree with Darwin’s descriptions and drawing, 
also in having a porous basis. Nevertheless their identity cannot 
be stated with absolute certainty, as the animals have evidently 
