PLANARIA ARETHUSA. 103 



not until the thirteenth of that month, that 

 the doubtful animals were restored to their 

 original grey. 



Though the proboscis be naturally single, 

 I once saw three in a monstrous planaria 

 of another species than what is treated of 

 in this section, which were all actively em- 

 ployed at the same moment. Apparently 

 no portion of it is lost by spontaneous divi- 

 sion of the body ; but how a new aperture 

 is made for its protrusion in a regenerating 

 fragment, I am ignorant. 



After taking the uses and properties of 

 this organ into view, w^e must henceforth 

 denominate that the orifice of the mouth, 

 which has hitherto been designed by natu- 

 ralists a conspicuous ventral pore in plana- 



rise. 



The mode of propagation peculiar to the 

 Planaria aretlmsa, is no less involved m 

 mystery, than the perpetuation of kindred 

 species, whose eggs and foetuses have been 

 sought in vain. Notwithstanding I have 

 carefully kept the same individuals for a 



