68 The MoUuscan Family Planorhidae 



similar in general form. The prostate shows fewer diverticula, however, and 

 the spermatheca is on a longer duct than in the specimens from Poland 

 examined, and they are figured more irregularly than was observed in the 

 specimens j^ersonally examined. A. Soos's figure of Gyraulus laevis I Aid.) 

 (1935, p. 27) shows a smaller number of prostate diverticula than appears 

 normal for the genus. The spermatheca is also on a longer duct than in 

 those species of the genus personally examined. No separate prostate duct 

 is indicated. 



American species examined differ but little from the European Gyraulus 

 albus. Gyraulus hirsutus (Gould), the nearest relative to albus, has from 

 twenty to twenty-two diverticula on the prostate as in albus (plate 15, 

 fig. 2). The seminal vesicle is practically the same. The penial complex 

 has a much shorter preputium with a vergic sac one and one-half times 

 as long as the preputium. This difference in form of the penial complex 

 easily separates albus from hirsutus (compare fig. 2, plate 14, with fig. 2, 

 plate 15). In Gyraulus deflectus obliquus (DeKay) there are forty divertic- 

 ula on the prostate which is much longer than either albus or hirsutus. The 

 prostate diverticula are also longer and club-shaped toward the end 

 (plate 16, figs. 11, 12). Plate 16 fully illustrates the genitalia of obliquus. 

 Gyraulus latestomus F. C. Baker (plate 19, fig. 9) has thirty-two diver- 

 ticula on the prostate and the penial complex resembles that of obliquus. 

 Gyraulus conve.vius cuius (Hutton) (plate 19, fig. 2) of India has about 

 twenty-five prostate diverticula. The penial comjilex is very long and 

 narrow but generally resembles that of hirsutus. The figures on plate 19 

 agree with tliose by Annandale and Prashad (Rec. Ind. Mus., XVHI, 

 p. 40) except that the spermatheca in the specimens examined is on a 

 much longer duct than is shown in their figure. 



Respiratory and Renal Systems. The pseudobranch of Gyraulus albus 

 (plate 14, figs. 3, 4) is broad, somewhat triangular, and flattened. The 

 pneumostome is broad (fig. 3, PS). Figure 4 shows the pseudobranch cut 

 open to indicate the vascular network of blood vessels. The rectum passes 

 through the pseudobranch, as in other genera of Planorbinae. In Gyraulus 

 hirsutus (plate 15, fig. 3) the pseudobranch is as broad as in albus. In 

 Gyraulus deflectus obliquus the pseudobranch was observed to be of several 

 forms (plate 16, figs. 13, 14, 15). It is in each case a broad, flattened 

 organ. Figure 15 is an unusual form, possibly pathologic. In Gyraulus 

 latestomus (plate 19, fig. 8) it is broad and flattened. In Gyraulus convexi- 

 uscidus, from India (plate 19, fig. 3) it is flat and very thin and the pneu- 

 mostome is very large. The pseudobranch appears to be similar in form in 

 species from Europe, America, and India. 



The kidney (plate 48) is long and narrow in obliquus (fig. 4, 9 mm. 

 long) and conve.xiusculus (fig. 17, 8.5 mm. long). In hirsutus (fig. 18, 2.5 

 mm. long) and albus (which has the same form as hirsutus) the kidney is 

 short and wide, quite unlike the kidney of the two species previously men- 

 tioned. It is similar to that of vermicularis (fig. 3). Sections through the 

 kidneys at about the middle show this organ to be flattened, the lumen 

 much wider than high, and the veins to be placed at each end at about the 

 center. Conve.vius cuius (fig. 8), hirsutus (fig. 19), and latestomus (fig. 11) 

 are similar in form, but obliquus (fig. 10) is higher in proportion to width 

 showing that the kidney is thicker than in the other species. There is no 

 ridge. The ureter is short in convexiusculus and obliquus but longer and 

 more tube-like in hirsutus and albus. 



