Subfcunilies, Genera, and Subgenera — Recent and Fossil 179 



In fig. 12, plate 42. the verge is shown in this condition, with the penial 

 gland (GLj extended crosswise of the preputial cavity. The end of the 

 verge of variety megas is shown in fig. 13, plate 42, indicating the centrally 

 located opening of the sperm canal with a small jienial papilla placed just 

 below and to one side of the opening. A circular ridge near the end of the 

 verge was observed in this specimen which did not appear in others 

 examined. 



In a specimen of variety tnegas (fig. 4. plate 42), the gland was some- 

 what contracted but showed well the trough-like canal or channel con- 

 necting the gland with the circular canal near the diaphragm. In this speci- 

 men, the side ridges or bands of muscle connecting the two pilasters with 

 this canal are well shown. A specimen from Winnebago Lake had the 

 verge and penial, gland extended from the male opening and lying on the 

 neck of the animal (plate 41, fig. 91. 



Female Organs (plate 41, fig. 10). The spermatheca (S) is irregularly 

 ovate, bulging in the center, with a wide duct (SD) about as long as the 

 spermatheca, the two parts together measuring about 2 mm. The vagina 

 (VG) is wide and a trifle more than 1 mm. in length. The uterus (U) is 

 the same width as the vagina and narrows only at the upper part of the 

 oviduct (OD). The uterus and oviduct combined are about 4 mm. long. 

 The nidamental gland (XG) is about 1.5 mm. long. The relationship of 

 the sperm duct, oviduct, ovisperm duct, carrefour, and albumen gland duct 

 is shown in fig. 10, plate 42 (of variety megas). The duct of the albumen 

 gland is quite long and folded in an S form. The albumen gland (plate 41, 

 fig. 7) is about 2 mm. long and half as wide. 



Hermaphrodite Organs. The ovotestis OT, (plate 41, fig. 10) occupies 

 a little more than one whorl (fig. 6). In section (fig. 4), it is seen to be 

 composed of twin, club-shaped diverticula, both glands entering the ovi- 

 sperm duct. Sections of variety megas are shown on plate 42, one near the 

 middle of the ovotestis (fig. 8) and one near the posterior end (fig. 9). The 

 ovisperm duct (free portion) extends about 1 mm. on each side of the 

 seminal vesicle and is without glandular projections or swellings. 



A related species, Promenetus innhilicatellus, formerly known as 

 Gyraidiis umbilicatiis, shows some differences and the anatomy of this 

 species is shown on plate 43. The seminal vesicle is about twice the di- 

 ameter of the ovisperm duct (fig. 1) and is bordered on both sides by 

 several more or less sharply pointed gland-like protuberances. Small 

 vesicles project from the ovisperm duct for a long distance (over 1 mm.) 

 below the seminal vesicle. The sperm duct (SPD) is short, and narrow 

 (less than 1 mm. long) and is a small tube. The jirostate (PRS) is about 

 1 mm. long and is composed of twenty diverticula which appear very long 

 and narrow when the prostate is in its natural position lying against the 

 uterus. A section about midway of its length (fig. 6) shows five supple- 

 mentary diverticula or six including the termination of the main diver- 

 ticulum. The vas deferens (YD) is a narrow tube about 3 mm. long. 



The penial complex (fig. 4) is about 1.5 mm. long and the preputium 

 and the vergic sac are of about equal length. The vergic sac is not much 

 narrower than the preputium. the latter having a swelling or ridge at the 

 upper part indicating the position of the diaphragm. There is one narrow 

 retractor muscle (R^I) attached to the upper part of the preputium and 

 a wide band of supporting muscle (S]\I) attached to the middle portion of 





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