Subfamilies, Genera, and Subgenera — Recent and Fossil 175 



(fig. 11, D). The verge (V) is sac-like, about 1 mm. long, and tapers to a 

 point at its lower end (fig. 12). The sperm canal extends through the center 

 of the verge and has a central outlet bordered by a small penial papilla 

 (fig. 8). 



Female Organs (fig. 4). The spermatheca (S) and spermathecal duct 

 (SD) are about 1.3 mm. long, the duct and gland of equal length and the 

 gland swollen to more than twice the diameter of the duct. The vagina 

 (VG) is 0.8 mm. long and 0.3 mm. wide the spermathecal duct entering it 

 rather high. The uterus (U) is about 2 mm. long and is but little wider 

 than the vagina. The nidamental gland is slightly wider than the uterus 

 and is located beneath the prostate. The oviduct (OD) is over 2 mm. long 

 and is of the same diameter as the sperm duct. It is somewhat convoluted 

 at the upper end, where there is a large carrefour (CF) which receives the 

 long duct from the albumen gland (fig. 3, DA, AL). The albumen gland 

 (AL) is large, about 1 mm. in diameter, somewhat triangular in shape, and 

 is folded for the passage of the intestine. 



Hermaphrodite Organs. The ovotestis (fig. 4, OT) occupies a little 

 more tlian one whorl and is composed of long, club-shaped diverticula ar- 

 ranged in pairs (fig. 7) , each pair bending to right or left or placed in the 

 center. There is a very short free ovisperm duct between the ovisperm duct 

 and the seminal vesicle, and a longer, narrow duct (2 mm. long) between 

 the seminal vesicle and the oviduct. A few vesicles extend down a part 

 of the ovisperm duct from the seminal vesicle. 



The genitalia of Planorbula jenksii are in most respects like those of 

 armigera. The prostate has about twenty-five rows of diverticula while 

 in armigera there are thirty rows. 



No figures of the genitalia of Planorbula have been published previ- 

 ously, except those by F. C. Baker (1928, p. 356, figs. 153, 154). The 

 figure of the entire genitalia (1928, fig. 153) is incorrect in several par- 

 ticulars, especially in the form of the prostate and the seminal vesicle. The 

 diagrammatic figure of a secion of the penial complex (1928, fig. 154) is 

 more nearly correct, but does not show the details of the penial gland. 



Respiratory and Renal Systems. The pseudobranch (plate 37, fig. 

 5, P) is rounded and has a ridge extending down the middle which con- 

 nects with a crest-like ridge on the rectum (R). The ridge on the pseudo- 

 branch is heavy and when bent over (as shown in the figure) causes the 

 pseudobranch to appear folded. There is a large pneumostome (PS). The 

 pseudobranch of jenksii is like that of armigera. 



The kidney (plate 45, fig. 3) is long and narrow (5.5 mm. long, 1 mm. 

 wide at the pericardium). The ureter is sharj^ly recurved and is directed 

 upward into the mantle cavity. The pericardium is about 1 mm. long. In 

 section (fig. 13, near middle), the kidney is seen to be much flattened, with 

 the lumen twice as wide as high and with a vein at each end. There is no 

 ridge on the kidney. 



Digestive System. The digestive organs (narrow stomach, crop, and 

 pyloris) are similar to those in Carinifex and Parapholy.r. The intestine 

 makes a loop around the stomach, passes backward to the liver, makes 

 another loop and runs forward to the rectum, ending in the anus over the 

 pseudobranch. There is a conspicuous blind sac or caecum. Both jenksii 

 and armigera have the same type of digestive system. The buccal sac is of 



