48 DEVELOPMENT. 



Littorina deposits its eggs in gelatinous masses, and the outer 

 portion of the albumen of each egg hardens into a sort of shell ; 

 but ordinarilj^ an egg capsule is formed, and then the separate 

 ova do not possess shells, but the capsule encloses a mass of 

 albumen which is common to all the ova within it— sometimes 

 several hundred. In this albumen the larv;e move about before 

 leaving the capsule for the outer world. 



The capsules are variously shaped and aggregated, and were 

 formerly mistaken for and described and figured as zoophytes. 

 It will assist us in our survey of their forms to present the 

 classification of these bodies which was proposed bj^ the cele- 

 brated Danish zoologist, A. Lund, based on their form and group- 

 ing, and in which almost all the variations are characterized. 



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. (Capsulce 

 coJicerentes) . 



1. The capsules open by a cleft. 



2. The capsules open by a round hole closed by a round operculum 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 by a round hole, which is closed by a lid. 



a. The capsules are sessile upon the basal membranes. (Sessiles.} 



o.. Tubiformes. 



b. The capsules are pedunculate, connected to the basal membrane by 

 a stalk. {PetiolatiB.) 



«. Oviformes. 



fi. Cyathiformes. 



y. Infundibiolifonnes. 



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. ( Capsulce 

 cohcerentes.) 



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

 {Capsulce adiMrentes.) 



a. The capsules are attached around an axis. 



b. The capsules are attached longitudinally on one side of an axis. 



a. Sessiles. 

 [•i. PetiolaUv. 



