188 The Molluscan Family Planorhidae 



cooperi, the prostate had but five rows of diverticula. The vas deferens is a 

 narrow tube ahiiost as long as the sperm duct. It is slightly enlarged near 

 the vergic sac. In Menetus sampsoni, the seminal vesicle (fig. 1 ) differs 

 from that organ in cooperi in being composed of four rounded swellings. 

 Only a few rather large vesicles occur on the ovisperm duct. 



The penial complex (fig. 12) is about 0.5 mm. long, the preputium (PR) 

 is sac-like or elongate-pyriform and is about twice as long as the ovate 

 vergic sac (VS). In sampsoni (fig. ID, the vergic sac is longer and wider. 

 There is one retractor muscle (RM) which is usually attached to the con- 

 striction between the preputium and the vergic sac (fig. 11). There are 

 several small supporting muscles on both sides of the preputium. The 

 penial complex was observed in several different forms in the material 

 examined. In one (fig. 3), the vergic sac was placed on the side of the 

 preputium, the gland being pushed upward, as occurs so frequently in the 

 genus Helisoma. In another specimen (fig. 4) , the preputium was much 

 swollen and the retractor muscle was attached to the preputium some dis- 

 tance below the vergic sac. 



Internally (fig. 5), there is a sac-like penial gland with a rather long 

 duct. This is shown to better advantage in Menetus sampsoni (fig. 10), 

 where the gland (GL) is much elongated and gradually diminishes in 

 diameter to the round duct, which follows the wall of the preputium (DC) 

 to the muscular ring or diaphragm separating the preputial sac from the 

 vergic cavity. The cup containing the vertical folds is small and is placed 

 at the end of the penial gland. There is a central duct running through 

 the gland as in Menetus cooperi callioghjptus. In a Texas specimen (fig. 2) , 

 the gland was somewhat different, resembling a pipe or trumpet. This might 

 have been abnormal. The verge (fig. 10, V) is elongated, narrowing to a 

 point at the lower end. The sperm canal has a central outlet. See also fig. 5. 



Female Organs. The spermatheca (fig. 12, S) is short and sac-like and 

 is connected with the very wide vagina (VG) by a wide duct twice as 

 long and half as wide as the spermatheca. The uterus (U) is wide, increas- 

 ing to about twice the diameter of the vagina in the region of the prostate, 

 where the still wider nidamental gland (NG) appears. The oviduct (OD) 

 is short and gradually narrows to meet the sperm duct. There is a carre- 

 four which lies between the oviduct and the albumen gland (not shown in 

 the figure). The albumen gland (AL) is very large and wide (almost half 

 as wide as long) and is composed of large vesicles. The intestine makes a 

 loop beneath the albumen gland (IN). 



Hermaphrodite Organs. The ovotestis (OT) is composed of relatively 

 few large, somewhat club-shaped diverticula arranged in pairs. A single 

 diverticulum filled with developing ova is shown in fig. 6. The diverticula 

 vary in form, being more swollen when filled with ova ready for discharge. 



Respiratory and Renal Systems, The pseudobranch of dilatatus (plate 

 40, figs. 7, 9) is about twice as long as wide and extends below the margin 

 of the foot in preserved specimens. It is somewhat folded on the side and in 

 a Texas specimen {sampsoni, fig. 8) formed a hollow cylinder. There is a 

 fluted crest on the rectum (R) which, however, does not appear on the 

 pseudobranch in the specimens examined. The anal opening (A) is jilaced 

 at the upper end of the pseudobranch. 



