116 The MoUuscan Family Planorhidae 



Internally, the penial complex is simple in all species studied and re- 

 sembles the condition observed in hoff)nani (plate 10, fig. 6). There are 

 three rather heavy pilasters, a small muscular ring or diaphragm between 

 the preputium and the vergic sac, and a very long verge completely 

 filling the vergic sac (V). The verge is narrow at the end with a central 

 sperm outlet (plate 10, fig. 9). 



Female Organs. These also differ in the three species. In hofjmani 

 (plate 10, fig. 2 1 the spermatheca is pyriform and is joined to the long and 

 narrow vagina by a duct twice as long as the spermatheca; in lucidum the 

 spermatheca (plate 11, fig. 3) is globular, much wider than in hoffmani, 

 and is connected with the vagina (which is shorter than in hoffmani) by a 

 duct a trifle longer than the spermatheca; in anatinum (plate 9, fig. 2) the 

 spermatheca is wider than in hoffmani but not as globular as in lucidum 

 and is attached to the narrow vagina by a duct almost three times as long 

 as the spermatheca. The uterus (U) is very long and narrow in hoffmani, 

 shorter and wider in lucidimi, and narrow in anatinum. 



The nidamental gland is long and wider than the uterus in all three 

 species. The oviduct (OD) is very long and narrow in hoffmani (about 5 

 mm. long), much shorter in lucidum (about 2 mm.) and very short in 

 anatinum (less than 1 mm.). There is a small and inconspicuous carrefour 

 (CF) in all species. The albumen gland is much elongated (plate 10, fig. 4). 



Hermaphrodite Organs. The ovotestis (OT) consists of a few club- 

 shaped diverticula placed in a double series. The ovisperm duct is much 

 longer in lucidum than in either hoijmani or anatinum (see plate 9, fig. 2; 

 plate 10, fig. 2; plate 11, fig. 3). 



Several specimens of lucidum had the male genitalia completely everted 

 and lying on the body of the animal (see plate 11). In fig. 1, the preputium 

 is fully everted and the verge is extended to its fullest extent. In fig. 2, 

 only the preputium is everted. In fig. 6, the organs are diagrammatically 

 shown so that the relationship of the different parts may be seen under 

 this condition. The flagellum, vergic sac, vas deferens, and retractor muscle 

 remain in the body of the animal just behind the male ojiening. This is 

 shown to better advantage in fig. 7. 



Pilsbry (1934, p. 59, fig. 6, F) figured the penial complex of lucidum 

 (from sketches by H. B. Baker). This figure differs from the specimens 

 here examined in having a shorter flagellum and in having the penial re- 

 tractor attached to the preputium instead of to the vergic sac. In all speci- 

 mens of Drepanotrema examined, the retractor muscle was inserted at the 

 end of the vergic sac near the flagellum and not at the summit of the 

 preputium. As shown in fig. 8 on plate 10 [hoffmani) , the vas deferens, 

 flagellum, and retractor muscle may be so closely pressed together and 

 bent downward at the summit of the preputium that relationship of the 

 muscle is difficult to see clearly unless the parts are separated, as shown in 

 fig. 4, plate 11 {lucidum). All specimens were torn apart to insure 

 accuracy in this statement. 



Pilsbry also figured the penial complex of Drepanotrema cultratum 

 (Orb.) (plate 76, fig. 10) which is similar to that of lucidum, the vergic sac 

 being but a trifle shorter than the preputium. The flagellum is somewhat 

 more than half as long as the vergic sac. Pilsbry 's figures are the only ones 

 previously published on the anatomy of Drepanotrema. 



