Prof. Allman on the Hydroid Zoophytes. 137 XV. — Notes on the Hydroid Zoophytes. By Prof. Allman. I. Laomedea flexuosa, Hincks. In the polypes of Laomedea flexuosa, the ectoderm of the ten-tacles is extended laterally between the^e organs for a distance of about a fourth of their entire length from their origin, so as to form a web-like membrane, similar to that already pointed out by Mr. Alder in L. acuminata. This peculiarity in a very common zoophyte seems to have been hitherto overlooked, though, in a morphological point of view, it is a character of much importance. II. The cxtra-capsular medusiform sporosacs (" meconidia ") of Laomedea, and the determination of the species in which they they are found. In a communication on the Reproductive Organs of the Hydroid Zoophytes, read last year before the Royal Society of Edinburgh *, I referred to the extra-capsular medusiform sporo-sacs, so well known from Loven's description of them in a zoo-phyte which he names Campanidaria [Laomedea) geniculata, and expressed my opinion that Loven's zoophyte was not truly Lao-medea geniculata, but L. flexuosa of Hincks, a species to which I referred similar bodies which I had myself examined. Mr. Alder, writing to me since then, suggests the possibility of the species which gives rise to these sporosacs being neither the one nor the other, but a distinct, though not yet discrimi-nated, species. As we know that both L. geniculata and L. flexuosa give rise also to a different kind of sexual bud, it will be at once seen that this question has an important physiological significance apart from its bearing upon simple descriptive diagnosis ; and I therefore availed myself of the first opportunity to inquire critically into the subject. The result has been a conviction that Mr. Alder's doubts are well-founded. A few weeks since, I obtained upon the shores of Cramond Island, in the Firth of Forth, a Laomedea, growing on the fronds of Fucus vesiculosus, and loaded with gonophores, most of which carried upon their summits the peculiar bodies under consideration. The only described species of Laomedea with which it is pos-sible to confound the Cramond zoophyte are L. flexuosa, L. ge-niculata, and L. dichotoma. From L. flexuosa, however, it dif-fers in the more elongated form of the polype-cells, in the more conical form of the gonophores, and in the absence of the web * Proc. Roy. Soc. Edinb. 1858.
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