434 Proceedings of the 



Last year I fed for some time several individuals of Helix 

 aspersa, with the intention of examining the structure of the 

 hermaphrodite gland when it should be in a favourable con- 

 dition. My attention was then drawn to a remarkable spiral 

 thread seen in all the specimens after coupling, projecting 

 from the female division of the sexual orifice, and trailing 

 along the whole length of the animal's body. Siebold, in his 

 " Anatomy of the Invertebrata,'' alludes to this thread in a 

 note, and suggests that it is the remains of a spermatophore, 

 and is secreted by the multifid vesicles ; but in both these 

 ideas he is decidedly mistaken. However, he refers to two 

 papers on the subject, and in one of these, by Carus, the 

 nature of the structure is perfectly apprehended. Carus saw it 

 in Helix arbustorum, and states that it consists of hardened 

 albumen ; that he found that it was situated in the long duct 

 of the spermatic vesicle, and that it passed from that to the 

 common genital opening, whence, after coupling, it issued gra- 

 dually, and was lost, until subsequently renewed. "Worthy 

 of remark," says he, " are two longitudinal folds on the inside 

 of the duct, as well as the diverticulum described by Brandt, 

 whose cavity may supply the first material for the nucleus of 

 the elastic body.* 



The observation which I wish to bring under the Society's no- 

 tice is, that in Helix aspersa the long tubule, which is indeed 

 only a greatly developed diverticulum inserted very low down 

 into the seminal duct, is the secretor of this spiral thread. 

 Towards the pairing time the duct gets very much elongated, 

 and at the same time stiffened, by the development of the thread 

 in it, and in consequence it can be no longer alongside of the 

 uterus, but is thrown into convolutions, and so becomes sepa- 

 rated from it except at the apex. During coupling the uterus 

 is contracted, and this convolutes the tubule still more, and 

 no doubt aids the expulsion of the thread. The lining mem- 

 brane of the tube is thrown into folds similar to those which 

 Carus describes in the diverticulum of Helix arbustorum. 



At the period of greatest development the superior extremity 

 of the tubule, for about half a line, is bent abruptly back upon 



* Muller's Archiv., 1835, p. 495. 



