258 THE CHICAGO ACADEMY OF SCIENCES. 



penis. The penis and penis sac are retracted by a set of pow- 

 erful muscles (RM, PSM, VD). A nerve starts from the cerebral 

 ganglion (CG) and after extending for a short distance divides, 

 one branch running to the head of the penis and the other 

 entering the penis sac (PN, PSN). The penis is generally yel- 

 lowish in color, sometimes very bright, while the penis sac is 

 grayish (in alcohol) or yellowish (living). The muscles are 

 white in color. 



The vas deferens is long and hairlike (F), and extends from 

 the head of the penis to the base of the penis sac where it be- 

 comes lost in the muscular tissue; it reappears at the opening 

 of the vagina where it becomes the duct of the prostate (PD); 

 this duct is rather long, very narrow and enlarges on the side 

 of the vagina into the prostate gland (PR), a cylindrical, fleshy 

 organ, well supplied with blood vessels and of a yellowish or 

 amber color. Posterior to the cylindrical portion, the prostate 

 becomes very much narrowed and flattened, whitish in color, 

 and near the albuminiporous gland it again enlarges into a 

 much folded organ of a grayish color. From this point the 

 hermaphrodite duct passes to the hermaphrodite gland. 



Female organs: (PI. xxxiii, Fig. D): The hermaphrodite 

 gland or ovotestis is made up of a number of rounded or lobu- 

 lated follicles, which are yellowish in color. The oviduct (or 

 hermaphrodite duct (OD) extends from the lower part of the 

 ovotestis to the albuminiparous gland, from which it divides, 

 one part forming the prostate and the other the uterus. The 

 albuminiparous gland (AL) is large and rounded and of a green- 

 ish color. The uterus (U) is at first trilobed, then becomes 

 smaller and rounded, then swells into a large, fleshy, cylin- 

 drical sack, the vagina (V), then contracts to form the vesti- 

 bule or atrium (A) and finds its exit behind the male orifice and 

 near the respiratory orifice. The uterus and vagina are yel- 

 lowish in color. The walls of these organs are made up of 

 strong muscular tissue. The spermatheca or receptaculum 

 seminis (S) is elongate-oval in form, of a pearly white color, and 

 connected with the vagina by a long, narrow duct (SD) which 

 enters the latter near the cylindrical portion of the prostate, 

 just above the atrium. The vagina is supplied with two stout 

 retractor muscles (VM). In the natural position the ovotestis 

 is folded in the lobes of the liver and is very strongly attached 

 to that organ.* 



*For an extended account of the anatomy of LimnEea see the writer's paper, Bull. Chi. 

 Acad. Sci., Vol. II, No. 3, from which the above description was mainly drawn. 



