24 Mr. Goodsir on the Anatomy of the Limneus involutus. 



to this species^ as it exists also in the L. Feregev\ and one si- 

 milar but more complex has been described and figured in the 

 ^ Annales des Sciences Naturelles^ for 1837^ page 112, by Van- 

 beneden as existing in the L.glutinosus. Vanbeneden describes 

 a median between the two large anterior ganglia, and an- 

 other between the two small stomato-gastric ganglia. 



*^ Cuvier in his memoirs on the Limnaus and on the other 

 gasteropod moUusks, mistook the testicle for the ovary, and 

 consequently reversed certain of the other reproductive or- 

 gans. Prevost of Geneva, in a paper published in the Trans- 

 actions of the Physical and Natural History Society of that 

 place for 1828, and in another contained in the ^Annales des 

 Sciences Naturelles' for 1833, pointed out this error, and de- 

 scribed the very beautiful structure, by means of which the 

 seminal fluid is conveyed along the cavity containing the eggs, 

 without coming in contact with them. This structure may be 

 distinctly seen in the Helix aspersa, in which it consists of a 

 groove, wdth the orifice of the duct at both extremities, run- 

 ning along the inner surface of the oviduct. When the fluid 

 is passing from the testicle this groove is converted into a 

 temporary tube by the close apposition of its lips ; a structure 

 similar to the groove in the true ruminating stomach. The 

 arrangement of the reproductive organs in L. involutus, al- 

 though different from that described by Cuvier in the L. stag- 

 nalis, is yet similar to that given by Prevost. The testicle, «, fig. 

 2. which is situated in the extreme whorls of the shell, sends 

 off a duct, which has attached to it in the middle of its course, 

 small follicles {b) of the same diameter as itself, which appear, if 

 carelessly examined, like duplications of the tube. The duct 

 then becomes closely connected with the point of junction of 

 the ovary and oviduct, runs along the latter for a short di- 

 stance, and opens into the acute extremity of an oblong sac (c), 

 which is closely but not intimately adherent to the oviduct. 

 This sac appears granular from the follicular arrangement of 

 its inner surface ; it is bulbous at its anterior extremity, near 

 which it sends off the second division of the seminal duct {d), 

 which running along the terminal extremity of the oviduct, 

 at length leaves it, and dives under the transverse muscles (e) 

 of the foot, as described by Cuvier in L. stagnalis, again 



