66 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



organ known as the capreolus. The above are the male organs of the 

 compound system. 



The female organs consist of the ovary, a linguiform body, sometimes 

 lobulated, at the posterior end of the genital system. The oviduct is 

 a long sac-like body, usually greatly convoluted in its course. It de- 

 creases in breadth at its anterior end, and gradually merges into the 

 vagina, a long tube-like body of uniform size to the common external 

 orifice ; into its lower end, called by Dr. Leidy the cloaca, enters the 

 penis sac, and above this enters also the duct of the genital bladder. 

 This last organ, as well as the bladder itself, varies greatly in size and 

 length, and forms an excellent specific character. 



The above is the simplest form of the genital system, all these organs 

 being absolutely necessary. It is often much more complicated by 

 having an accessory, very much lengthened duct to the duct of the gen- 

 ital bladder, by various forms of vaginal prostate glands, often with 

 complicated accessories ; with one or more dart sacs entering into the 

 vagina, containing a dart of various shape. The penis sac also some- 

 times has curious and varied accessories. All these organs may be 

 found in some species of any given genus, while other species may have 

 only the organs necessary to the genital system. 1 I am induced, there- 

 fore, to consider the details of the generative system to be only a spe- 

 cific character. As a generic character we can rely only on the position 

 of the external orifice of the system, and on the position of the testicle 

 as well as the form of the cceca which compose it. Thus Glandina, 

 Zonites, and Ariolimax have the external orifice under the mantle, while 

 usually it is found behind the right eye-peduncle. Again Limax, Ario- 

 limax, Prophysaon, Hemphillia, Arion, Glandina, and Succinea have the 

 testicle free, and formed of aciniform coeca, while in the genera of dis- 

 integrated Helix and others it is composed of fasciculi of elongated cceca 

 commingled with the substance of the upper lobe of the liver. 



GENERAL REMARKS UPON THE JUNCTION OP DIFFERENT PORTIONS OF THE 

 GENERATIVE APPARATUS, AND THE STRUCTURE OF ITS TISSUES. 



The testicle was mistaken by Swammerdam, Cuvier, and others for 

 the ovary, and the latter organ and prostate gland for two portions of 

 the testicle. A microscopic examination of these different organs at 



1 For instance, in Arionta we find the necessary organs only in Townsendiana, but in 

 Nicklinianaa.'D.di other species a great variety cf accessory complications. 



