A memoir upon the aquiferous system and the oviducts of Lamellibranchiate Mollusks by Messrs. Rolleston and Robertson, was read before the Royal Society at the Meeting on the 3rd of February, 1859. The abstract of this memoir, contained in the ‘Annals and Magazine of Natural History,’ reached me in the month of July; and I was not a little surprised to find that a structure which I had so elaborately studied in the course of my various journeys to the sea-shore, and which I had carefully described in a number of species, was something quite different from what I had imagined it to be. "Without entering into minute anatomical details, which would not tend to elucidate the question, I find that Messrs. Rolleston and Robertson consider that the organs, the ducts, and the orifices supposed to be the ovaries or their excretory ducts, are, in fact, nothing but an aquiferous apparatus, and that the openings placed on each side of the foot are the excretory orifices of this system. They discover elsewhere the ducts whose office is to convey away the products of the genital glands. The enunciation of an opinion so opposed to what I, in common with many other authors, had maintained, seemed to require a recurrence to direct observation. But on repeating my examination of Cardium edule , Tellina solidula , Mactra stultorum and Donax anatina , I have precisely verified my previous conclusions. On throwing injections into the genital orifices, the sexual glands have become turgid; and on examining fragments of such injected genital glands microscopically, the injected substance was seen mixed with the ova or spermatozoa. These facts may be observed with especial ease in Cardium edule .