193 



The following communications were read : 



I. " Note respecting the Circulation of Gasteropodous Mollusc a 

 and the supposed Aquiferous Apparatus of the Lamelli- 

 branchiata." By M. H. LACAZE DUTHIERS. Communicated 

 by Professor HUXLEY. Received October 19, 1859. 



A memoir upon the aquiferous system and the oviducts of Lamelli- 

 branchiate Mollusks by Messrs. Rolleston and Robertson, was read 

 before the Royal Society at the Meeting on the 3rd of February, 1 859. 

 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 stu- 

 died 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 appa- 

 ratus, 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 recur- 

 rence to direct observation. But on repeating my examination of 

 Cardium edule, Tellina solidula, Mactra stultorum, and Donax ana- 

 tina, 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. 



In addition to this, I have seen ova actually laid by living females 

 of Modiolce and Mytili, one of the valves of whose shell was removed, 

 on irritation of the genital orifice ; and in others the ova or the 

 spermatic fluid may be made to pass out of their orifices, at the 

 breeding season, by pressing gently upon the foot. 



In Spondylus gcederopus the genital orifice is situated in the sac 



