102 The Molluscau Family Planorhidae 



plainly seen. The retractor muscle (RM) is attached to the preputium at 

 the point where the gland joins the pilaster (fig. 12, SB). 



The verge is swollen above and tapers to a narrow diameter for about 

 half its length (V). The sperm canal has a central outlet but there is no 

 papilla. There is a narrow muscular ring or diaphragm (D) between vergic 

 sac and preputium. The two short flagella (FL) are hollow and under high 

 power show a minutely punctate surface at the upper rounded end (fig. 11). 



Female Organs (fig. 15) . The spermatheca (S) is long, ovate, sac-like 

 and is joined to the short, wide vagina (V) by a long, tube-like duct, which 

 is twice the length of the spermatheca. The uterus (U) is twice as wide 

 as the vagina, and shorter than the spermatheca and its duct. The nidamen- 

 tal gland (NG) is longer than the uterus, much swollen and about half 

 as wide as long. The oviduct (OD) is short (about 0.5 mm.) and about 

 the same diameter as the uterus. There is a large, bulbous carrefour (CF) 

 which receives the duct from the long and narrow albumen gland (AL; 

 also fig. 10). 



Hermaphrodite Organs. The ovotestis (OT) has about thirty club- 

 shaped diverticula jilaced for the most part in a double row (fig. 7). The 

 ovisperm duct (SO) is very long (about 2 mm.) and of small diameter. 



Odhner (1929, p. 32, fig. 13) figures the genitalia of this species agree- 

 ing in most resi)ects with the material personally examined. A few points, 

 however, are figured differently from the position observed in the speci- 

 mens studied. The prostate is shown as having thirteen diverticula 

 rather widely spaced on the sperm duct, cjuite different from the long, 

 crowded diverticula personally observed (see plate 2, fig. 15, PES). The 

 ovotestis diverticula are shown extending in pairs from a short duct which 

 enters the ovisperm duct. In this species, as well as others of this subfamily 

 and of Planorbinae, the ovotestis diverticula arise in pairs directly from 

 the ovisperm duct, each diverticulum entering the duct separately (see 

 plate 2, fig. 7). No mention is made of a separate prostate duct or of a 

 gland in the preputium. An elongated object in the upper part of the 

 prej^utium is shown in Odhner 's figure which might represent this organ. 



Odhner's figure of the radula of Hippeutis complanatus differs some- 

 what from the radula as personally examined, there being no interstitial 

 cusps between the larger cusps. The formulas of Odhner's specimens agree 

 exactly with ours. 



Respiratory and Renal Systems. The pseudobranch (plate 2, fig. 13) 

 is small, rather narrow, and })ierced above by the rectum (P). The pneu- 

 mostome is very large. 



The kidney (plate 46, fig. 17) is rather short (1.5 mm.) and wide, the 

 greatest width being almost one third of the length. The ureter is not 

 sharply reflexed as in Segmentina, but extends horizontally into the mantle 

 cavity. A cross section below the middle (fig. 18) shows the kidney to be 

 flattened, the lumen rounded with the veins placed at the upper corners 

 of the lumen. There is no superposed ridge. The kidney of Hippeutis is 

 quite different from that of Segmentina (compare fig. 17, plate 46, with 

 fig. 22, plate 47). 



Digestive System. The stomach (plate 48, fig. 12) is elongated, as in 

 Segmentina. The intestine loops around the stomach and liver, and there 



