Suhjamilies, Genera, and Subgenera — Recent and Fossil 67 



shell in several species is covered with short, hair-like projections of the 

 periostracum (hirsute). 



Animal. External appearance (plate 70, fig. 5). The head bears the 

 long, filiform tentacles characteristic of the Planorbinae with the eyes at 

 the inner base. In general form the animal does not differ greatly from the 

 figures of Tropicorbis on plate 78. No pigmentation, however, shows 

 through the shell. 



ANATOMICAL CHARACTERISTICS 

 PLATE 14 {Gyraulus albu.^) 



GENITALIA. Male Organs (fig. 7) . Seminal vesicle (SV) less than 1 

 mm. long, composed of a few large diverticula or glands three or four times 

 the diameter of the ovisperm duct. Sperm duct about 2 mm. long, of small 

 chameter. Prostate (PRS) relatively long (1.5 mm.) consisting of about 22 

 long (less than 0.5 mm.) diverticula attached to a separate prostate duct 

 which is more than twice the diameter of the sperm duct. The free portion 

 of the prostate duct is very short (0.2 mm.) and is of the same diameter 

 as the sperm duct which it joins to form the rather short (1.2 mm.) vas 

 deferens. A cross section through the prostate near the anterior end shows 

 the sperm duct behind the prostate (fig. 9, SPD). 



The penial complex (fig. 2) is cylindrically elongated, a trifle more than 

 1 mm. long, the vergic sac (VS) somewhat shorter than the preputium 

 (PR). There is one long retractor muscle (R^I). The vas deferens is not 

 enlarged as it enters the vergic sac. Internally (fig. 1) the preputium has 

 thick walls, two pilasters, a muscular ring or diaphragm (D), and a de- 

 pendent papilla (PP). The vergic sac has thin walls which increase in 

 thickness toward the preputium. The verge (V) is elongate-pyriform, 

 narrowed at the lower end where there is a stylet (ST). The stylet (fig. 8, 

 ST) is dark brown, dagger-like with a ridge extending down the center. 

 The opening of the sperm canal (SC) turns to one side above the stylet 

 and has its exit on the side of the verge. 



Female Organs. The spermatheca (fig. 7, S) is elongate-pyriform, 

 about 0.5 mm. long. It is joined to the vagina by a short, narrow duct about 

 half as long as the spermatheca (SD). The vagina (VG) is very short and 

 wide. The uterus (U) is wider than the vagina and the nidamental gland 

 is wide and made up of many large diverticula (fig. 6, NG I . The uterus and 

 gland are hidden in the figure by the large prostate. The free oviduct (fig. 

 6, OD) is a short and narrow tube, looped beneath the prostate. Figure 6 

 shows the relationship of the nidamental gland diverticula, the oviduct, 

 the prostate, the sperm duct, which forms a loop, and the method of junc- 

 tion to form the ovisperm duct. The narrow duct of the albumen gland 

 and its connection with the oviduct is shown. The albumen gland is 

 squarish or oval in shape and is composed of large gland cells. It contains 

 cavities for the loop of the intestine, over which it lies (fig. 5). 



Hermaphrodite Organs. The ovotestis (OT) consists of a double row 

 of pyriform diverticula attached to a large ovisperm duct (fig. 10). At the 

 posterior end of the ovotestis the diverticula are crowded together (fig. 11). 

 Several diverticula had developing egg cells. The ovisperm duct (SO) is 

 divided into two parts, one at each end of the seminal vesicle (fig. 7, SO). 



The figures on plate 14 agree with that of Germain (1931, p. 533, fig. 

 545). His figure, however, is not very clear. Soos's figure (1917, p. 55) is 



