152 The MoUuscan Family Planorbidae 



appears to descend to the middle of the preputium. In fig. 8, the penial 

 complex of H. campanulatum canadense is shown with the preputium 

 notably pushed upward. 



Female Organs (fig. 15). The spermatheca (S) is very long (2.5 mm.), 

 sac-like and tapers to the long (5.5 mm.), narrow spermathecal duct (SD). 

 The vagina (VG) is 1 mm. long and is very narrow. The uterus (U) is 

 long (7.5 mm.) and narrow. The nidamental gland (NG) is about 4 mm. 

 long, very wide, and sac-like. The free oviduct (OD) is about 2 mm. long 

 and is about twice as wide as the sperm duct. There is a large, elongated 

 carrefour (CF). The albumen gland (fig. 2) is ovately rounded and is 

 composed of many small follicles. The space for the passage of the intes- 

 tine is conspicuous (fig. 2, IN). 



Hermaphrodite Organs (fig. 15). The ovotestis (OT) consists of 

 eight or more rows of club-shaiied diverticula, some of which may branch 

 two or three times, as shown in the section fig. 4 (FOV), this branching 

 rendering the counting of rows difficult. The figure shows fourteen rows on 

 the surface and but eight entering the ovisperm duct. The free portion of 

 the ovisperm duct (SO) is 3 mm. long near the oviduct but only 1 mm. 

 long near the ovotestis. 



The only previous description and figures of the genitalia of Helisoma 

 camqiamdatum are by F. C. Baker ( 1931, p. 585, plate iv) where the penial 

 complex is shown (plate 27. figs. 10-11 of this work). 



Respiratory and Renal Systems. The pseudobranch (plate 27, fig. 13) 

 is leaf-shaped, broadly ovate, with a ridge down the center which is a con- 

 tinuation of the ridge on the rectum (R). The pneumostome is large. 



The kidney (plate 45) is similar to that of Pierosoma as represented 

 by Helisoma trivolvis. Sections through the kidney of H. campamdatum 

 irisconsinense are shown in figs. 15, 16, and 17. In fig. 15, the section 

 through the upper part shows a large rounded lumen with a large vein on 

 each side near the middle. The ridge does not begin until lower down on 

 the kidne3^ Figure 16 shows a section through the middle of the kidney. 

 The lumen is larger than in fig. 15, the veins are at the lower part on each 

 side, and the ridge is just beginning to show. In fig. 17, taken through the 

 lower part of the kidney, the lumen is smaller, the veins relatively larger, 

 and the ridge forms a high crest. All varieties of campamdatum show 

 essentially this form of kidney. 



Digestive System. The general digestive system does not differ from 

 that of Helisoma trivolvis. The buccal sac is much elongated, differing in 

 this respect from many of the species of Pierosoma. 



The jaw (plate 49). The superior jaw (of smithi, fig. 11) is elongated 

 and low, somewhat arched, its face covered with vertical striations as 

 shown in fig. 20. The lateral jaws are about as in Pierosoma. 



The radula (plate 62). Typical campamdatum (fig. 1) has a w'ide, 

 bicuspid center tooth, the cusps not reaching the lower margin of the base 

 of attachment. The lateral teeth (1-7) are squarish, tricuspid, with the 

 mesocone bluntly rounded, the entocone and ectocone aculeate. The inter- 

 mediate teeth (8-9) have smaller, sharper mesocones and the entocone 

 and ectocone are modified by the addition of smaller cusps. The marginal 

 teeth (10-13) are long and narrow, somewhat claw-like, with the entocone 

 wide and armed with from four to eight small cusps. The mesocone is small 



I 



