SEXUAL ORGANS. 119 



brated Danish zoologist, A. Land, based on tlieir form and 

 grouping, and in which almost all the variations are character- 

 ized. 



First Class. 



Masses of capsules irregular. The egg-capsules by their union 

 form irregular masses, ■ 



First Order. The egg-capsules are attached to each other. 

 {Capsulse cohserentes.) 



1. The capsules open by a cleft. 



2. The capsules open by a round hole closed by a round oper- 

 culum or lid. 



Second Order. The egg-capsules are attached to a common 

 membrane, which is attached to some foreign body, and are 

 separated from each other. 



1. The capsules open by a cleft. 



2. The capsules open b}^ around hole, which is closed by a lid. 



a. The capsules are sessile upon the basal membranes. 

 {Sessiles.) 



a. Tuhiformes. 



b. The capsules are pedunculate, connected to the basal 

 membrane by a stalk. {Petiolatse.) 



a. Oviformes. 



/?. Cyathiformes, 



y. Infundibuliformes. 



Second Class, 



Masses of capsules regular. The egg-capsules by their union 

 form regular masses. 



First Order. The egg-capsules are attached to each other. 

 ( Capsulse cohserentes.) 



Second Order. The egg-capsules are attached to a common 

 basis (Capsulse adhserentes). 



a. The capsules are attached around an axis. 



b. The capsules are attached longitudinally on one side of 

 an axis. 



a. Sessiles. 

 /9. Petiolatse. 



How these capsular bodies (xvii) are developed is still a 

 mystery. 



Androgynous gastropods (Pulmonata, xviii, 8) present two 

 distinct types of sexual organs: 1, Monotremata, in which the 

 genital orifices, are confounded in a single cloaca, as in the helices; 

 2, Ditremata, in which the genital orifices are more or less 

 distant, as in Limnsea. 



