NATURE OK PLANARI^S. 



proper place, in the order of nature. Cer- 

 tain species now excluded, ought obvious- 

 ly to be annexed to it ; and possibly seve- 

 ral which are there comprehended, should 

 be detached. Adjusting this point, how- 

 ever, would involve discussions which it 

 may be desirable for the present to avoid. 



The planaria, on external inspection, 

 seems allied both to the leech and the snail, 

 but more akin to the latter, and, at the 

 same time, possessing parts and properties 

 belonging to neither. Intermediate ge- 

 nera probably remove it from each ; for, 

 as our knowledge of the creation ex- 

 tends, subordinate distinctions produce an 

 interval between analogous races of ani- 

 mals, occupied by shades always becom- 

 ing slighter and slighter, until the origi- 

 nal characters are lost in some common 

 object. One comprehensive division, that 

 which shall engage most of our attention 

 in this place, may be defined, " naked, 

 flattish in a state of abstinence, provided 

 with a proboscis protruding from the mid- 



