1869.] On the genus OncMdium. 93 



substance. It is not clear to what purpose it exists, but probably it is 

 in some way connected with the ovarium or the testis. 



The ovarium (as, in fig. 5, or in fig. 2) is of a deep yellowish colour and 

 contains eggs only ; these being of an oval form and of various sizes, 

 according to their stages of development ; the whole is attached to the 

 uterus by a short string. — It is generally stated that in the Pulmonata, 

 the hermaphrodite gland secretes ova and spermatozoa, but in this case I 

 am certain that they are secreted in two different glands, the ovarium 

 containing, as I stated, merely eggs. The testis (t) is a distinct 

 foliated, or more or less dendritic, purely white gland, which is readily 

 I distinguished by its viscous, jelly-like substance. Under the microscope, 

 the contents of the gland had a granular appearance, mingled with a few 

 fat cells,and numerous long thread-like bodies, — spermatozoa. From the 

 testis a very thin hollow string issues, accompanying the oviduct in its 

 entire length and terminating by a special minute pore (g) in the 

 same cavity as the oviduct. This string is evidently the beginning 

 of the vas deferens, which continues externally in a grove between 

 the foot and the mantle. 



The largest portion of the generative organs are occupied by the 

 albuminous gland (ag) which is of a soft purplish colour, consisting 

 of very numerous folicles attached to short prolongations of the 

 uterus. The albuminous substance has a finely granular appearance 

 under the microscope and is very viscous, adhering to everything that 

 comes in contact with it. It absorbs water to a large proportion 

 swelling up readily in it. 



The male copulative organ is at the front end of the body, situated 

 more or less closely to and under the right eye-pedicle. The semen 

 issues, as stated above, first from the genital pore (g), is then con- 

 ducted in an open canal along the right side between the foot and the 

 mantle, enters the body through a very fine pore (vdo in fig. 5), below, 

 or on the side of, the right buccal appendage, close to the penis opening ; 

 then passes through a thin long tube (vd) which is variously twist- 

 ed round the penis (p) lying on the right side of the body. This 

 tube, the continuation of the vas deferens is about 5 inches long, 

 the last inch, or so, forming the penis, which is considerably 

 hardened and straight, situated in a somewhat wider tube and 

 provided at its termination with a short flagellum. In many 



