SubjaniiUes, Genera, and Subgenera — Recent and Fossil 59 



yeiuinal vesicle, as in the ii'enus Planorbis. The portion between the seminal 

 vesicle and the ovotcstis is enlarged in septemgyratus and Icucostomus 

 (plate 7, figs. 2, 6) but is of small diameter in spirorbis and vortex. In the 

 first two species the enlargement is of the same diameter as the seminal 

 vesicle, of which it may be a part. The portion of the ovisperm duct be- 

 tween the seminal vesicle and the oviduct is a long, slender, smooth tube 

 in leucostoinus, but in vortex, septemgyratus, and spirorbis there are small 

 pustule-like bulgings which ai)i)ear to be glandular extensions of the sem- 

 inal vesicle. 



The genitalia of the four species here recorded are in the main similar 

 to Buclmer's fig. 11, tafcl 4, which is copied by Simroth. Germain's figure 

 of rotundatus (=leucostonius) is similar but lacks detail (1931, pp. 527, 

 539). The prostate is shown too long as compared with the Poland speci- 

 mens personally examined. Soos's figure (1917, p. 50) is like those in this 

 work, as is also the figure of vortex (p. 53). 



Respiratory and Renal Systems. The pseudobranch is large, narrow, 

 and flattened in all species examined. It is pierced by the rectum which is 

 long and narrow. The pneumostome is cylindrical and in the specimens 

 examined is rolled into a cylindrical tube with a large cleft extending its 

 whole length. It varies in length in the different species (plate 6, fig. 6 

 vortex, fig. 11 spirorbis, and plate 7, fig. 1 leucostonius) . 



The kidney (plate 47) is very long and narrow, the glandular portion 

 occupying only a small part of the entire length. In spirorbis (fig. 13) it 

 is 5 nun. long and about 0.3 mm. wide but in vortex it is 12 mm. long and 

 over 0.3 mm. wide. The ureter is very short and is sharply bent upward 

 into the mantle cavity. The pericardium is very short as compared with 

 total length of the kidney. Cross sections show no evidence of a ridge. In 

 vortex (fig. 14) the kidney is as thick as wide and the veins are placed at 

 the base of the rounded lumen. In leucostomus (fig. 15) the kidney is wider 

 than high with the veins lower on the lumen. In these species the kidney is 

 somewhat triangular in shape to fit the sharp angle caused by the pe- 

 ripheral carina of the shell. In a cross section of spirorbis (fig. 16) the 

 kidney is seen to be very wide and much flattened with the veins near the 

 middle of the lumen. The kidney of Anisus does not differ in any essential 

 way from that of Phinorbis. 



Digestive System. The stomach, buccal sac, and general digestive sys- 

 tem are similar to these organs in Planorbis. The jaw (plate 50, fig. 25) 

 is similar to that of Planorbis with about twenty plates on the upper part. 

 The side jaws are also fragmented. 



The radula (plate 67, fig. 6, spirorbis) formula is 15-1-15 or 16-1-16. 

 The numbers of rows of teeth vary from 185 to 195. Central tooth with two 

 spade-shaped cusps reaching nearly to the lower edge of the base of attach- 

 ment. Lateral teeth (1-10) tricus]')id, about as wide as high at first but 

 becoming narrower toward the marginal teeth. There is but one inter- 

 mediate tooth (11), four-cuspid, with the reflection short and wide. 

 INIarginal teeth (12-15) narrow, four-cuspid, the reflections very short and 

 wide. The fourth cusp appears as a splitting of the ectocone. The formulae 

 for the other species examined are as follows: 



sejptemgyratus 16-1-16 with 130 rows 

 vorlex 16-1-16 with 142 rows 

 leucostomus 16-1-16 with 130 rows 



