PLANARIA. 107 



PLATE XIV. 



FIG. 36. Planaria haustrum the back, 

 37. The same enlarged, belly 



2. All the preceding Planariae are inhabitants of the seas ; they 

 have a certain correspondence of figure, being thin, flat, scarcely thicker 

 than writing paper, and swimming with violent action in the water. 

 But these characters chiefly apply to the first four ; the diminutive size 

 of the last impeding observation. They are fierce and voracious animals. 

 I have never seen any resembling them in the fresh-waters of Scotland. 



There are some marine Planariae, however, of different aspect and 

 habits, participating more of the general features of such as dwell in lakes, 

 ponds, and marshes, which merit a few observations. 



a. PLANAEIA HEBES The Sluggish Planaria. Plate XVI. figs. 3, 4. 



Length above three lines ; breadth above half a line. Body plump 

 above, flattened below ; anterior extremity even ; eyes, two in the middle 

 of the neck. Colour universally wax-yellow ; when emaciated cream-yel- 

 low or dingy white. The colour is somewhat dependent on the quality 

 of the food. 



The whole figure of this, which is a marine Planaria, bears much 

 resemblance to the Planaria panniculata of fresh- waters. 



Two specimens survived eight or nine months. 



PLATE XVI. 



FIG. 3. Planaria Iwbes. 



4. The same, enlarged. 



/>. PLANARIA LACTEA The Milky Planaria. Plate XVI. figs. 5, 7, 8, 9. 



Plate XV. figs. 4, 5 6. 



This being the type of the genus Planaria usually selected by na- 

 turalists, greater interest may be, perhaps, felt in its history. But there 



