60 Descriptions of Preparations. 



or parieto-splanclinic portion of the sub-oesophageal mass. Two 

 of these are the parietal nerves of the right side ; and the third, 

 which is seen to be double at its termination, is the visceral nerve 

 in connection with the aorta. The hermaphrodite gland is lodged 

 in the concavity of the penultimate and ante-penultimate coils 

 of the liver, which occupy the lowest part of the preparation on 

 the right hand. From the gland a convoluted hermaphrodite duct 

 passes up to a spleen-shaped body, the albuminiparous gland; and 

 after this junction, the duct passes upwards again as a much 

 thicker tube consisting of two parts, one of which is much plicated, 

 whilst the other is a riband made up of granulations. These two 

 elements of the tube are not differentiated from each other till 

 just opposite the convex end of a cylindrical hollow muscular 

 organ, the dart-safc, where they separate and form, the one the 

 oviduct, and the other the vas deferens. The vas deferens loops 

 round the right tentacle, and joins the basis of the penis-cylinder 

 at the point where the flagellum, or organ for secreting the sper- 

 matophore, also joins it. This latter organ is of great length, 

 ending blindly at the lowest part of the preparation, and to the 

 right of it is placed the pedunculate receptaculum seminis of 

 commensurate, as obviously of correlated, length. The retractor 

 muscle of the penis is attached to it a little below the point of 

 junction to it of the vas deferens and flagellum. Below the penis 

 are seen the multifid vesicles, forming ultimately two main trunks. 

 These vesicles, the dart-sac and the flagellum, are peculiar to, 

 though not uniformly found in, European Helicidae. The flagellum 

 is never found in American species, and the dart-sac and the 

 multifid vesicles are much rarer in these representatives of the 

 family than in the European species. Some, however, of the 

 American Limacidae possess them, which is not the case with 

 the Old World slugs. Much variability, both as to size and as 

 to constancy, is, as is usually the case with structures specially 

 developed in particular families, and not generally possessed by 

 the entire order to which they belong, observable in these struc- 

 tures, as investigated in one species after another in the families 

 possessing them. 



For the anatomy of the Pulmonate Gasteropoda, see Leidy, vol. i. 

 p. 198, in Binne/s Terrestrial Air-breathing Molluscs of the 



