(185) 
Luchu Islands, in De Toni’s »Sylloge Algarum« and in Solms’ 
»Monograph« (though the allied genus Aalzcoryne occurs), induces 
me to make a few remarks on this curious alga. 
The Luchuan specimen of Acetfabularia was collectet on the 
coast of Yuntanza in the Island of Uchina or Okinawa. It consists 
of fully developed pileate thalli of a pale-white colour, each 
furnished with a well-calycified stalk of some 60 mm long, at the 
upper extremity of which a circular cap of 14 mm in diameter is 
borne. The number of the sporangial rays of the latter is about 
sixty-five, and each ray is kept apart at the base. These rays are 
firmly connected together by means of a membrane, which, being 
thickened at the margin of the cap, appears, through transmitted 
light, highly refractive. That this membrane is not of calycified 
nature, as is observed to be in the cases of Acetabularia major and 
A. Gigas collected in Eastern Asia, was proved by successive appli- 
cations of decalycifying tests'!), to which it gave no reaction. The 
structure of the corona is not readily recognizable in my specimen, 
but the inferior corona is more distinct than the superior one, both 
being furnished with tufts of hairs. From these observations, there 
is but little doubt that the specimen belongs to Acetabularia medi- 
terranea, Lam. 
Later on, Prof. J. Matsumura of the Imperial University of 
Tokyo, kindly submitted to me some beautiful specimens of Ace- 
tabularia, collected by him on the same island in 1897. These 
specimens proved on examination to be identical in species with 
the specimen above referred to. In them, however, the cap is of a 
greenish colour, which may be accounted for by its growing either 
in shady places or at a great depth. The length of the stalk in 
these specimens is 37—81 mm, with a cap of 9-—11,5 mm diam. 
In one of the young plants, the stalk is 37 mm, and the cap 
3,5 mm diam. 
It is of great interest to note that in the latter specimens, I 
found some shoots with cap-whorls. These shoots are 13—20 mm 
long, with some twelve whorls, the upper ones being larger, but 
becoming gradually smaller toward the base. The entire shoots are 
pale white, the upper whorls being green. Solms, in describing 
these cap-whorls, calls attention to the affınity between Acetabulartia 
and Halicoryne. 1 might append to his statement, that Aalicoryne, 
which has these whorls in its mature state, may perhaps represent 
the ancestral form of Acetabularia. 
With regard to the nature of the cap, together with its coronae, 
of this interesting genus, there are at present some differences of 
opinion. Falkenberg?) suggests that the cap is a highly compli- 
cated aggregation of hair-whorls placed together around the main 
axis of the stem, which abruptly terminates and does not extend 
beyond the cap; while the one hair-whorl goes to the inferior corona, 
another to the sporangial rays, and several to the superior corona. 
In this view, the cap is regarded as an equivalent to the hair-whorl 
in the shoot of Acetabularia. 
!) Solms, loc. cit. p. 15. 
2), Falkenberg, P. — Die Algen im weitesten Sinne. (Encyclopädie der 
Naturwissenschaften, Botanik, Il, 1884.) 
