^i< PLANARIA arethusa. 



habits of living creatures, not on isolated 

 features only. 



Five of the planariae arethusae being sup- 

 plied with fish containing a quantity of 

 clotted blood, in a short time evidently ap- 

 peared to have fed voraciously. The lar- 

 gest, instead of a thin, flat, meagre figure, 

 resulting from scanty aliment, now exhibit- 

 ed a semicylindrical shape, and was con- 

 verted from the predominant leaden tinge 

 to a dull brown colour. Transverse streaks 

 of black or deep grey, constituting the 

 darkening shade of the animal, became very 

 conspicuous by the enlargement of the bo- 

 dy, which had apparently augmented in 

 length as well as in breadth. Something 

 similar to an elliptical intestine, which I 

 conjectured to be the stomach, was, be- 

 sides, perceptible ; and this having also 

 been seen in others, induced me to think 

 that here it was certainly so, more especial- 

 ly as its termination might be in that point 

 designed by naturalists the ventral pore. 



