Subfamilies, Genera, and Subgenera — Recent and Fossil 131 



of the prepiitium through which the penial ckict extents (GL, DG). In 

 section (fig. 7), this gLand is seen to be composed of two cup-like cavities, 

 one, the inner cup, has several large glandular folds (GF) and the other, 

 the outer cup, has several smaller folds attached to the wall of the cup 

 (OC). The larger folds extend transversely across the cavity as shown in 

 fig. 11, GL. The small cup is at the extreme end or tip of the gland. The 

 gland duct enters the smaller cavity, as shown in fig. 7, DC. There is a 

 narrow ridge or diaphragm which separates the vergic sac space from the 

 preputial cavity. The gland duct enters the vergic space above this dia- 

 l^hragm as shown in fig. 11. The verge (V) is pyriform or reversed conic 

 0.9 mm. wide at the upper part and tapering to a point. The sperm canal 

 has a central outlet. 



Female Organs (plate 28, fig. 14). The spermatheca (S) is bulbous, 

 wide and about 1 mm. long. Its duct (SPD) is 2 mm. long, rather wide and 

 increases notably in diameter at the lower end where it enters the short 

 ( 1 mm. long I vagina. The vagina narrows to about half its diameter at 

 the female opening (VG). The uterus (U) is about 3 mm. long and is as 

 wide as the diameter of the spermatheca. The nidamental gland (NG) is 

 short (about 1 mm. long) and sac-like. The oviduct (OD) is about as long 

 as the uterus, very wide, and bears the nidamental gland about midway of 

 its length. The albumen gland (AL) is somewhat longer than wide and is 

 composed of many small, gland-like vesicles (fig. 14, AL) . 



Hermaphrodite Organs. The ovotestis occupies the first and a part of 

 the second whorls and is composed of ten or more rows of club-shaped 

 diverticula of unequal length (fig. 13, plate 28). The free portion of the 

 ovisperm duct is very short (about 0.7 mm.) both anterior and posterior 

 of the seminal vesicle. 



The genitalia of Helisoma scalare examined agree perfectly with the 

 figures published by Pilsbry (1934, fig. 1, b, c, d). The peculiarities are 

 the wide and pyriform penial complex, the short gland duct, the elongated, 

 two-cupped penial gland and the lai'ge, sacculated seminal vesicle. 



The several varieties under the name of Helisoma duryi (Wetherby) 

 show some differences from scalare in their anatomy (plate 33). In 

 Helisoma duryi normale Pilsbry, the genitalia are much elongated, due to 

 the more widely-coiled shell (fig. 15). The seminal vesicle (SV) is much 

 shorter in comparison (2 mm. long) and the gland sacs are larger. The 

 sperm duct (SPD) is a long and narrow tube (7.5 mm. long). The prostate 

 (PRS) is more elongated (5.5 mm. long) and contains a greater number 

 of diverticula. The prostate duct is longer and the space between the 

 entrance of the sperm duct and of the vas deferens is several times wider. 

 The vas deferens (VD) is a long and narrow tube (over 20 mm. long). 

 The spermatheca (S) is much longer and larger (3.5 mm. long) and is 

 more elongate-ovate in shape. Its duct is longer (5.5 mm.) and much 

 narrower. The uterus and nidamental gland are longer and narrower and 

 the oviduct (OD) is narrow and much elongated. The free portion of the 

 ovisperm duct is also longer. The albumen gland (AL) is more irregular 

 in shape. 



The penial complex is usually short and wide but varies somewhat in 

 this respect (see figs. 8. 9. 12. 17. 18). Normally (figs. 17, 18), the preputial 

 sac is as long as, or only a trifle longer than, the vergic sac, and is always 



