180 The Molluscan Family Planorbidae 



the preputium. A small supporting muscle may be present on the preputium 

 below the retractor muscle. 



Internally, the penial complex is like that of exacuous (fig. 3). There 

 is a large penial gland (GL) which may be folded back as shown in fig. 

 10. In section (fig. 11), it is like that of exacuous. There is an open, canal- 

 like duct (see fig. 9). The verge (V) is short and wide, with a central 

 opening of the sperm canal bordered by a distinct penial papilla (fig. 12). 



In the female system (fig. 1), there is a short spermatheca (S) with a 

 wide duct twice as long as the spermatheca (SD). The vagina (V) is wide 

 but shorter than in exacuous. The uterus (U) is wide and short and there 

 is a swollen nidamental gland (NG). The oviduct (OD) is longer than in 

 exacuous. The relationship of the oviduct, sperm duct and ovisperm duct 

 is shown in fig. 7. The albumen gland is somewhat quadrangular in form 

 and is composed of large vesicles (fig. 5). 



Of the hermaphrodite organs, the ovotestis is composed of paired 

 diverticula. In the specimens examined, many of the diverticula were 

 gravid (plate 43, fig. 1, (3T; fig. 8). The ovisperm duct differs from that of 

 exacuous by having a number of small swellings on one side of the duct for 

 half the length of the portion between the seminal vesicle and the oviduct. 

 A portion of the ovisperm duct between the seminal vesicle and the 

 ovotestis is without gland-like swellings. 



The penial complex of Menetus e.vacuou-s is figured by Baker ( 1928, p. 

 357, fig. 154). The retractor muscle is shown with an attachment to both 

 the preputium and the vergic sac. This feature was not observed in any 

 specimens more recently examined and this figure must be considered 

 abnormal. All material studied, of exacuous and umbilicatellus, had a 

 single retractor without two branches for the vergic sac and the preputium. 

 The same criticism extends to fig. 157 on p. 362 of the work mentioned. 



Respiratory and Renal Systems. The pseudobranch appears somewhat 

 variable in form, the variation being largely due to the amount of expan- 

 sion of the organ. In specimens of e.vacuous from Winnebago Lake, Wis- 

 consin (plate 41, fig. 8), it is large and leaf-like. In an example from 

 Wainwright Park, Alberta (plate 42, fig. 1), it is fully expanded, wide and 

 rounded below, with the anal opening conspicuously placed on one side 

 within the area of the i:)seudobranch. It is somewhat folded in the middle. 

 In a specimen of variety megas from Paul Lake, British Columbia (plate 

 42, fig. 2), the pseudobranch is rounded, and there is a smooth ridge extend- 

 ing over a part of the rectum and forming a thickened border to the pseudo- 

 branch. In umbilicatellus (plate 42, fig. 6), the pseudobranch is rounded in 

 one specimen and folded in another (plate 43, fig. 2). In these examples, 

 the anal region is outside of the area of the pseudobranch. There is no 

 decided ridge on any specimen examined and the ridge on the rectum is 

 not like that in Helisomatinae. 



The kidney (plate 46, fig. 3) of exacuous is 3.5 mm. long and about 

 0.5 mm. wide, rather long and narrow. The ureter is a long tube and turns 

 at right angles to the long diameter of the kidney. It borders the thickened 

 mantle margin on the inside. The pericardium is less than 1 mm. long. A 

 cross section of the kidney near the middle (plate 46, fig. 4) shows an 

 ovate lumen with a small vein on each side. There is no superposed ridge. 

 The kidney of umbilicatellus is of the same shape and general nature as 



