Subfamilies, Genera, and Subgenera — Recent and Fossil 137 



Hermaphrodite Organs (fig. 15). The ovotestis (OT) occupies about 

 one whorl of tlie slieU. It is composed of about thirteen rows of diverticula 

 which radiate from the ovisperm duct. In a cross section near the anterior 

 end (fig. 9), there are six cliverticula entering the ovisperm duct, four of 

 which branch twice, one is simple, unbranched, and one is branched four 

 times. The branching is not uniform throughout the ovotestis. The free 

 portion of the ovisperm duct (SO) is short, that portion near the ovotestis 

 being very short (about 1 mm.). The end near the oviduct is longer (1.5 

 mm.). A portion of the duct beyond the seminal vesicle (for about 1.5 mm.) 

 is provided with small vesicles along the side which are probably to be 

 considered as parts of the seminal vesicle. 



No figures other than those by the waiter (1923, 1931) have been pub- 

 lished. The chief characteristic is the large, wide, and somewhat pyriform 

 preputium and the very long penial gland duct. This duct is similar in 

 mature specimens of the different races and species, but there is some 

 variation in the details of the sexual organs, as would be expected. 



The genitalia of the races of Helisoma trivolvis vary in minor details 

 which are figured on plate 29. In H. t. pseudotrivolvis { = lentum, figs. 1-6), 

 there is considerable variation. Figure 1 shows the penial complex a trifle 

 wider than in typical trivolvis. In fig. 2, the penial complex is vertically 

 sectioned showing a wider verge and a somewhat differently shai)ed penial 

 gland. Figure 3 shows the manner in which the penial gland duct is coiled 

 on the outside of the preputium (DC). In fig. 4, the penial gland is shown 

 in vertical section, the cup being somewhat diagonal. As this gland is 

 capable of some muscular contraction and expansion this variation in 

 shape is of no taxonomic importance. In fig. 5, the preputial sac has been 

 pushed upward placing the vergic sac on the side of the preputium. The 

 form of the penial gland, the verge, and the great length of the penial 

 gland duct is indicated. In fig. 6, the penial gland has been protruded from 

 the male opening and is lying on the neck of the animal, near the female 

 opening. 



The genitalia of a race of trivolvis [lentum) from the type locality, 

 New Orleans, Louisiana, are shown in figs. 7-13. Figure 8 shows the gen- 

 eral form of the penial complex. In fig. 11, the penial gland has been 

 extended from the male opening, and is shown in its typical cup-shaped 

 condition. Figure 12 shows the gland exserted with the verge beside it, also 

 exserted. In fig. 13, the shape of the entire verge of this specimen is shown. 

 It is peculiarly shaped at the distal end. In fig. 7, the penial complex is 

 shown in its typical position w^ien the gland is exserted from the male 

 opening. The cup-shaped gland (GL) is normal. Characteristics of the 

 verge are shown in figs. 9 and 10. Figure 9 shows the entire verge which 

 has been sectioned in two places to show^ the location of the sperm canal 

 near the center of the verge. The waist-like constriction just above the 

 middle of the verge shows where this organ was compressed when it was 

 protruded through the muscular ring or diaphragm. The shape and central 

 position of the sperm canal outlet is shown in fig. 10, from the front and 

 from the side. The small papilla at the end of the verge is well shown. This 

 feature is characteristic of all members of the group Pierosoma. 



The large race of trivolvis (macrostomum) differs little from the typi- 

 cal form. Figures 14 and 16 on plate 29 show the normal condition of the 

 penial complex and fig. 15 a condition in which the preputium has been 

 greatly pushed upward. 



