Dublin Microscopical Club. 207 increase to the size of Y by September, it might then be 45 millim. by 56 millim, by next June. It is also probable that in confinement the young Carcini do not develop exactly with the same rapidity as they would in their natural haunts. Doubtless the environment, the temperature, and possibly also the quantity of water and the amount and nature of the food available will all have their influence on the rapidity of growth. PlIOCEEDINGS OF LEARNED SOCIETIES. DUBLIN MICROSCOPICAL CLUB. October 18, 1883. Camijanularia verticillata. — Prof. Macintosh exhibited a specimen of Campanulnria verticillata differing from the type of the species in that the caUcles have even rims instead of denticulate ones. The specimen was dredged in about 12 fathoms water off Greystones. Sections of Chiton. — Prof. Haddou exhibited transverse sections of Chiton (Trachydermon) ruber, showing the presence of an oviduct, contrary to W. H. Dall's statement, the so-called " ovarian fenestras " being merely the folded lips of the external openings of the oviducts. Spore-bearing Nostoc. — Prof. M'Nab exhibited a portion of an unidentified Nostoc (which had presented itself in one of the conser-vatories at Glasnevin Botanic Gardens) in a fertile condition, that is to say, showing spores ; these occurred in chains of several in a continuous row, elliptic and notably wider than the ordinary joints of the filaments, and seemingly showed no very noticeable relative distribution as regards the hetcrocysts. This is the second fertile Nostoc which has been noticed in this country, though several species have been foimd in that condition by Dr. Bornet, who has been so successfully studying the group. Characters of the Hairs of Acanthus sj)inosus. — Mr. Greenwood Pirn showed hairs from the anthers of Acanthus spinosus. These were of two kinds — one short and straight, forming a thick close brush along the edges of the suture of the anthers ; the other longer and more flexuous, and situated on the dorsal portion of the antheis. The short straight hairs had their surfaces curiously reticulated into labyrinthiform folds of every conceivable shape, whilst the dorsal hairs were only longitudinally striate. The position of the latter differed according as they Avere growing on one of the posterior pairs of stamens, whose anthers are in apposition, or on the ante-rior pair, which are free throughout.