40 PLANARIA PANNICULATA. 



in propagating by eggs; from which, accord- 

 ing to experiments made in the month of 

 September, the young were excluded ex- 

 actly in twenty-one days. The eggs are 

 deposited on leaves ; and the plexus of 

 the common marsh iris prove a favourite 

 receptacle, where the vicinity of the plant 

 admits of it. These eggs are originally 

 of a light colour, which speedily darkens 

 with exposure, until becoming brown, but 

 not so deep as that of the eggs of the 

 black planaria. Applied to the micro- 

 scope, each is discovered to be an exact 

 ovoid, of the most perfect and regular fi- 

 gure, with a smooth shining shell. I have 

 not ascertained whether more than one is 

 produced by an individual planaria; but the 

 number of included young varies in differ- 

 ent eggs, and they are, compared with 

 others, of large dimensions at the moment 

 of exclusion. Four young issued from one 

 egg, while from another only a single animal, 

 uncommonly large, was hatched. At first 

 they are almost white to the naked eye ; 



