HELICODONTA OBVOLUTA. 55 
the VESICULA SEMINALIS is rather large, the bulb white, and the stalk red with 
pigment evidently resident in the epithelium ; and André says the pedicle shows 
a longitudinal furrow similar to that shown in a grain of wheat, and the free 
extremity there is a slightly trilobed glandular body, connected by an excessively 
thin pedicle from one of the lateral lobes. The FREE OVIDUCT is curiously slender 
and long, and bears high up the small oval SPERMATHECA on a long and slender 
Fic. 81. Fic. 82. Fic. 83. Fic. 84. 
Fic. 81.—Reproductive system of Hledicodonta obvoluta (after a greatly enlarged dissection and 
sketch by Prof. Boycott). 
a.g. albumen gland ; d.s. vestigial dart-sac ; #7.¢2. vestigial mucus-gland ; of. ovotestis ; ov. oviduct ; 
pr. prostate; f.s. penis-sheath; 7. penial retractor; sf. spermatheca ; v. vagina or free-oviduct ; 
v.s. vesicula seminalis. 
Fic. 82.—Proximal portion of sexual system of Hedicodonta obvoluta (after Moquin-Tandon), 
showing the approximate natural positions of the various parts. 
Fic. 83.—Cephalic retractors (after a greatly enlarged dissection and sketch by Prof. Boycott). 
4.r. buccal retractor; #.7. penial retractor; ~.7. rectal retractor; ¢.7. retractor of ommatophores, the 
adjoining muscles arising from the same stem serve the lower tentacle and lip of their respective sides. 
Fic. 84.—Alimentary system of Hedicodonta obvoluta (after a greatly enlarged dissection and 
sketch by Prof. Boycott). 
6.6. buccal bulb; c. crop; ~ rectum; s.gé. salivary glands; s¢. stomach. 
stem ; immediately beneath if is an elongate thin walled blind vermiform sac, 
slightly swollen at end, destitute of muscle-fibres, and fairly full of amorphous 
white flocculent particles, but there are no large calcareous cells, such as are often 
found in the genital passages ; this is probably a MUCUS-GLAND. 
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Seen rams. aaete 
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1G. 85. Fic. 86. Fic. 87. 
Fic. 85.—Section through assumed vestigial mucus-gland of Hedicodonta obvoluta, highly magnified 
(after a drawing by Prof. Boycott). 
Fic. 86.—Section through the assumed vestigial dart-sac of Helicodonta obvoluta, highly magnified 
(after a drawing by Prof. Boycott). 
Fic. 87.—Vesicula seminalis of Hedicodonta obvoluta with adjacent parts (after a greatly enlarged 
dissection and sketch by Prof. Boycott). 
a.g. albumen gland ; 4.d. hermaphrodite duct ; ov.sf. ovispermatoduct ; v.s. vesicula seminalis. 
Another, but much shorter ececum, quite different in structure, is attached to 
and opens into the mucus-gland before merging into the free oviduct, which is 
probably a vestigial DART-SAC, which has, however, now lost all traces of the crys- 
talline love-dart it formerly possessed, but still retains the thicker walls and a fairly 
