Subfamilies, Genera, and Subgenera — Recent and Fossil 143 



section at the proximal end of the ovotestis (see fig. 17, OTj. The albumen 

 gland ( AL) is squarish and is made up of small follicles. 



The penial complex (fig. 14) has a pyriform i)rei)utium 4 mm. long 

 and a sausage-shaped vergic sac 3 mm. long (PR, VS). The penial gland 

 duct (DC) is of medium length (9 mm. long) and is a narrow tube. The 

 retractor muscle (RM) is wide and is divided into two main branches, 

 united at their attachment near the upper part of the preputium. The sup- 

 l)orting muscle (SAD is rather narrow and is branched several times in its 

 attachment to the upper jiart of the preputium on the opj^osite side from 

 the retractor muscle. 



Internally (fig. 11), the preputium has a large penial gland (GL) which 

 is attached to the. wall of the preputium by a thick neck or base. Sec- 

 tioned vertically (fig. 13) the penial gland is seen to have a large cup 

 bordered by large vertical folds (GF). The base of the cup has many 

 folds to which the penial gland duct is attached (DC). One specimen of 

 fraskii had a bifid tentacle (fig. 16). 



The genitalia of Helisonia trnskii are peculiar in the large prostate, the 

 elongated spermatheca on an unusually long duct, and in the generally 

 long and narrow uterus and vas deferens. It is different from californiense 

 in the size of the prostate and in the size and length of the spermathecal 

 duct. The shorter penial gland duct allies traskii with californiense and 

 separates it from plexatum. 



Another large species found in California is Helisoma occidentale 

 (Cooper), living characteristically in Klamath Lake, Oregon. Unfortu- 

 nately, the material had been preserved in formalin and the anatomy could 

 not be worked out in a satisfactory manner. The penial complex is like 

 that of californiense figured on plate 32, fig. 3. The vergic sac, however, 

 is more elongated at the distal end. The greater number of specimens 

 examined had the penial complex as shown in fig. 10, the preputium 

 pushed upward and the vergic sac attached to the side about halfway 

 between the extremities of the penial complex. The penial gland was about 

 as in traskii (fig. 13). The verge, coiled in the vergic sac, is shown in fig. 9. 

 Other details are not available from these specimens. 



Respiratory and Renal Systems. The pseudobranch of Helisoma tri- 

 volvis (plate 24, fig. 12) is very wide, somewhat bilobed, with a narrow 

 crest or ridge extending down the rectum (R) and over the pseudobranch 

 at about the center. The anal opening is to the left of the ridge. There is a 

 large pneumostome (PS). 



The shape of the pseudobranch does not vary to any degree in the 

 different species and races of Pierosoma, excepting in the general shape 

 which in many cases is broadly rounded below and not bilobed (see plate 

 25, fig. 11). Several of these are figured on the following plates: pilsbryi, 

 plate 25, fig. 3; infracarinatum, plate 25, fig. 11; truncatum, plate 26, fig. 

 11; subcrcnatinn, plate 30, fig. 16; californiense, jilate 32, fig. 4; traskii, 

 plate 32, fig. 15. 



The kidney of Helisoma trivolvis (plate 44, fig. 2) is elongated, 12.5 

 mm. long and 2 mm. wide at the upper part near the pericardium. The 

 ureter is 1 mm. long and is directed backward, parallel to the length of the 

 kidney. There is a conspicuous crest or ridge extending down the center of 

 the kidney from just below the pericardium to within 1 mm. of the lower 



