126 The Molluscan Family Planorhidae 



The verge is often extended into the preputial cavity as shown in figs. 2, 3, 

 and 4 on pLate 22. 



Female Organs (plate 23, fig. 11). The spermatheca (S) and its duct 

 are 5 mm. long, the spermatheca elongated, sausage-shaped and slightly 

 less in length than the duct, which is rather wide and enlarged as it enters 

 the long (1.5 mm.) and narrow vagina. The uterus (U) is about 5 mm. 

 long, widening upward to the nidamental gland (NG), which is about 

 2 mm. long and 1 mm. wide. The oviduct (OD) is about 4 mm. long and 

 0.3 mm. in diameter. There is a large carrefour (CD into which the small, 

 narrow duct of the albumen gland enters (DA). The albumen gland (fig. 7) 

 is squarish in form, about 2.5 mm. in diameter and is composed of small 

 follicles. Near the albumen duct the lobules are much larger than in the 

 body of the gland. A depression crosses the gland on the under side mark- 

 ing the space occupied by the intestine. 



Hermaphrodite Organs (fig. 11). The ovotestis (OT) consists of 

 many rows of club-shaped diverticula having a pavement-like appearance 

 from the surface of the gland. In section (fig. 10), the ovotestis is seen to 

 be composed of about a dozen diverticula extending fan- wise from the 

 ovisperm duct. The free portion of the ovisperm duct (SO) is somewhat 

 shorter, between the seminal vesicle and the ovotestis, than between the 

 seminal vesicle and the oviduct, but about 1 mm. in both regions. The larger 

 portion of the ovisperm duct is occupied by the seminal vesicle. 



The genitalia of the races of Helisoma anceps, as far as they have been 

 examined, are remarkably uniform. In specimens of Helisoma anceps 

 percarinatum from Douglas Lake, Michigan, there was some variation in 

 the form of the retractor muscle, this being often divided into several 

 branches toward the columella muscle (plate 22, figs. 2, 3, 4). In one 

 specimen (fig. 4) there were two muscles, an abnormal condition. 



Respiratory and Renal Systems. The pseudobranch (plate 23, fig. 4, P) 

 is squarish in shape, rounded below, pad-like, with a distinct ridge passing 

 down the center from the rectal region. The pseudobranch is 2 mm. wide 

 and about 1 mm. high. The rectum is very wide and there is an irregular 

 crest or ridge extending down the center (R). This ridge extends backward 

 on the rectum about a cjuarter of a whorl. It narrows notably as it nears 

 the anal end of the rectum. The pneumostome (PS) is not notably large. 



The kidney (plate 44, fig. 1) is 7 mm. long and 2 mm. wide at the 

 upper (pericardial) part, tapering to about 1 mm. wide at the lower part. 

 The ureter is less than 1 mm. long and is sharply reflexed parallel to the 

 long axis of the kidney. The pericardium is nearly 2 mm. long and 1 mm. 

 wide. There is a large and conspicuous superposed ridge extending from 

 just below the pericardium to the urethral portion of the kidney and going 

 beyond the kidney almost to the mantle margin. 



In cross section (fig. 7), this ridge, at the i)oint in fig. 1 marked by 

 the arrow, is seen to form a long fold which extends over the kidney 

 causing it to appear rounded in a ventral view of the kidney, as shown 

 in fig. 1. The lumen is regularly rounded and the two blood vessels appear 

 on each side at the lower part of the section. A small ridge to the left of the 

 lumen is shown in the figure. This ridge in the mantle is present in all 

 species of the family. 



A cross section of the kidney of Helisoma anceps latchfordi (fig. 8), 

 taken at about the middle of the kidnev, shows a less extensive ridge (RK) 



