Subfamilies, Genera, and Subgenera — Recent and Fossil 125 



is about 14 mm. long, somewhat smaller in diameter than the sperm duct. 

 It is still further diminished in diameter as it emerges from the muscular 

 tissue to enter the jienial complex (plate 23, fig. 3, VD). Near the summit 

 of the vergic sac the vas deferens enlarges to form an epiphallus (EPI). 



Tlic penial comjilex (plate 23, fig. 3) is a short, somewhat pyriform 

 organ about 4 mm. long. The preputium (PR) is very wide (1.7 mm.) and 

 about 2.5 mm. long. The vergic sac (VS) is somewhat bullet-shaped, 1.5 

 mm. long and 1 mm. wide. There is no marked constriction between the 

 preputium and the vergic sac. There is a wide retractor muscle (RM) 

 attached to the preputium just above the male opening. On the right side 

 of the preputium there is a group of supporting muscles (S^I). This group 

 may form a wide, solid band or it may be broken up into ten or twehT 

 smaller muscular bands. The supporting muscles are attached to the roof of 

 the mantle cavity. There is a short (2 mm. long), narrow, external tube or 

 duct (DC) on the outside of the preputium and adherent thereto. This 

 penial duct tapers to half its diameter as it enters the junction of the 

 prejiutium with the vergic sac. 



Internally (fig. 2) the penial comjilcx shows two cavities, an upper 

 vergic space and a lower preputial space, separated by a muscular ring 

 or diaphragm (D) which is capable of great contraction and expansion 

 (see fig. 5). In the preputial space there is one large, vertical fold or pi- 

 laster (PL) and several smaller vertical ridges. Attached to the wall of the 

 preputium at the upper end of the large pilaster is a rounded, cup-shaped 

 penial gland (GL). In section (fig. 1) this gland is seen to have the cup- 

 shaped, bulbous termination divided into two parts, an upper portion with 

 smooth or only slightly developed vertical fokls (OC) and a lower portion 

 (LC) lined with heavy vertical folds (GF). The floor of this cup is covered 

 with pavement-like folds, from which a narrow duct (DC) extends through 

 the neck of the gland and emerges through the bodv wall of the preputium 

 and becomes the external penial duct. A section through the region at the 

 junction of the two spaces (fig. 6) shows the relationship of the muscular 

 ring or diaphragm (D) to the gland duct, the latter penetrating the thick 

 wall of the lower portion of the vergic sac and opening into this cavity just 

 above the diaphragm. In fig. 11, plate 22, the outer cup of the gland is 

 turned back to expose more fully the folds of the inner cuji (Helisoma 

 an reps percarinatian) . 



Tlie A'orgc (plate 23, fig. 2, V) is normally short and wide and tapers 

 abruiitlv to a narrow point. In fig. 1 on plate 22 {Helisoma anceps latch- 

 fordi) it is shown well-extended, exhibiting an elongated, cylindrical form, 

 the supporting muscles (MS) plainly indicated at the upper end near the 

 top of the vergic sac. The enlarged epiphallus is also indicated. At the 

 terminal end of the verge the seminal opening is placed in the center of the 

 organ with a small, sharp appendage or papilla extending slightly below 

 the end of the verge. In fig. 10 on plate 22, the end of the verge is shown 

 with this feature enlarged to show the pointed pajiilla and the centrally 

 located seminal opening. 



The penial complex may assume a number of shapes, depending uj^on 

 the sexual condition of the animal. Often it is seen as shown in fig. 8, 

 plate 23, the penial gland pushed upward causing the com]ilex to assume 

 a bilobed aspect. The penial gland and the verge may sometimes be seen 

 l^rotruding from the male ojiening and lying on the neck of the animal. 



