VII 



MOLLUSC A GENITAL ORGANS 



235 



This apparatus, in Limncea, consists of a large evaginable terminal widening, into 

 which the vas deferens projects in the form of a papilla. Blood pressure causes the 

 penis sheath or prreputium to be evaginated through the genital aperture, into which 



FIG. 191. 



FIG. 192. 



FIG. 191. Genital organs of Limnaea stagnalis (after Baudelot). 1, Male genital aperture ; 

 2, larger penis tube (penis sheath) ; 3, protractors ; 4, smaller penis tube ; 5, vas deferens ; 6, pro- 

 stata ; 7, flattened widening of the vas deferens ; 8, hermaphrodite duct ; 9, hermaphrodite gland ; 

 10, part of the digestive gland (liver) ; 11, albuminous gland ; 12, nidamental gland ; 13, uterus ; 

 14, pear-shaped body ; 15, receptaculum seminis ; 16, vagina ; 17, female genital aperture. 



FIG. 192. Genital organs of Oncidium celticum (combined from the figures of Joyeux- 

 Laffuie), somewhat diagrammatic ; only part of the vas deferens is drawn. 1, Male genital aperture ; 

 2, penis sheath (pneputium) ; 3, penis papilla ; 4, vas deferens ; 5, uterus, the seminal furrow iu 

 the uterus is indicated by dotted lines ; 6. caecum of the uterus ; 7, oviduct and vagina ; 8, csecal 

 appendage ; 9, receptaculum seminis ; 10, female genital aperture ; 11, albuminous glands ; 12, caecum 

 of the hermaphrodite duct, 13 ; 14, hermaphrodite gland. 



it is again withdrawn by means of a retractor. In other species of Oncidium , the 

 copulatory apparatus is complicated by the occurrence of accessory penis glands and 

 variously-shaped cartilaginous armature. 



