No. 465.] GENITALIA OF LYMNEA. 667 
examined, the male and female organs opening by separate 
orifices, that of the former being behind the right tentacle and 
that of the latter at the base of the neck, not far from the pul- 
monary opening. The genitalia occupy the median portion of 
the body cavity and are the most conspicuous organs when the 
animal is opened from the back (Fig. 2). The female organs 
closely embrace the alimentary tract, stomach, and esophagus, 
the ovotestis being imbedded in the liver near the posterior part 
of the animal. The male organs lie to the right of the buccal 
sac, the vas deferens being coiled up between these two organs. 
The relations of the different organs cannot be made out until 
they are spread out and separated from each other. 
Discussion OF SPECIES. 
Lymnea stagnalis appressa Say. (Figs. 3, 4.) 
Male Organs. — Penis-sac very large, cylindrical, rather wide 
at the external opening and narrowing toward the distal end 
where the penis is attached. The penis is very short and rather 
thick, about one fourth the length of the penis-sac. There are 
three sets of protractor muscles on the penis-sac and two sets of 
retractor muscles. A large, thick muscle is inserted in the head 
of the penis at one end and is attached to one of the retractor 
muscles. The vas deferens is very long and extends from the 
penis to the base of the penis-sac where it is lost in the columella 
muscle, to appear again at the base of the vagina as the duct of 
the prostate gland, which is long and hair-like and enters the 
prostate in a rounded, bulbous-shaped organ, which gradually 
narrows until it enters the ovisperm duct. 
Female Organs. — The vagina is a narrow, cylindrical organ 
about as long as the penis-sac. At the distal end it forms a 
large, rounded, more or less pyriform uterus, which narrows to 
form the oviduct, which is a tortuous, much folded organ, doubled 
upon itself several times. This organ narrows and unites with 
the ovisperm duct, which leads to the ovotestis or hermaphro- 
dite gland, which is made up of rounded or lobulated follicles 
and is strongly attached to the liver. The albuminiparous gland 
