560 THE INVERTEBRATA 



in the Animal Kingdom, and may be indeed said to be physiologically 

 adapted to a plant diet (cp. Teredo^ p. 587). The intestine runs from 

 the stomach, within the liver, and then as the rectum in the roof of 

 the mantle cavity. 



The reproductive organs are extremely complicated (Fig. 385 A), 

 but a function has been assigned to each part of what appears to the 

 elementary student as an unmeaning tangle of tubes. Eggs and sperm 

 are produced in the same follicle of the ovotestis, a small white gland 



o.d. gph. sptd. 



Fig. 385. Helix pomatia. A, Reproductive organs. B, Section through the 

 copulatory organs of two mating snails at the moment of the transference of 

 the spermatophores. After Meisenheimer. The organs of the two individuals 

 are indicated by shading sloping in different directions, al.gl. albumen gland ; 

 d.s. dart sac; fl. flagellum; m.gl. mucous glands; o.d. oviduct; p. penis; 

 rec.sem. receptaculum seminis; ret. p. retractor muscle of the penis; sph. 

 spermatophore ; spt. spermatheca ; spt.d. spermathecal duct ; sp.d. sperm duct ; 

 o gl. hermaphrodite gland (ovotestis), and ^ d. duct. 



in the apex of the visceral hump. But while ripe sperm is found 

 throughout a large part of the year, mature eggs only occur for a very 

 short space indeed. Both eggs and sperm pass from the ovotestis to 

 the albumen gland through the hermaphrodite duct, the terminal 

 portion of which is a pouch [receptaculum seminis) where sperm is 

 stored and fertilization is said to occur. After fertilization, the eggs 

 enveloped in albumen from the gland enter the rather voluminous 

 female duct, which runs almost straight to the exterior. They then 



