PLANARIA ARETHU8A. 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, we must henceforth 

 denominate that the orifice of the mouth, 

 which has hitherto been designed by natu- 

 ralists a conspicuous ventral pore in plana- 

 riae. 



The mode of propagation peculiar to the 

 Planaria arethusa, is no less involved in 

 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 



