PLANARIA ARETHUSA. 109 



general contour was distinguished by a re- 

 gularity which belongs to perfection only. 

 On the thirty-first of March, a considerable 

 enlargement had succeeded, and the young 

 planaria possessed all the properties and 

 characteristics of full grown animals. At 

 this period, also, the tail of the parent was 

 completely renewed, but the substituted 

 part marked by a certain pellucidity inva- 

 riably indicative of reproduction. Both the 

 original animal, and the offspring which 

 constituted the separating fragment, are 

 represented from life. Fig. 11. 14. 



Propagation in this way is a much more 

 rare occurrence, than with the preceding 

 species, in which it is described. A num- 

 ber of the felinse being indiscriminately 

 taken from still water, on the twentieth 

 of July, some proved of the largest size, 

 others minute, and several had undergone 

 spontaneous division ; they either want- 

 ed the lower extremity, or portions de- 

 tached were in progress of accjuiring the 

 defective organs. The following day, I 



