112 PLANARTA. 



utility to shew other naturalists the fallacies to which they may be ex- 

 posed. 



In as far as I can judge, this Planaria is not to be identified with 

 the Planaria torva, as described and represented by authors. 



Of above 100 specimens, collected from what is called the Dropping 

 Well at Foulden, in Berwickshire, the largest exceeded seven lines in 

 length, by a line in breadth. They were of various colours. Some al- 

 most white, cream- yellow, brownish-yellow, blackish, grey, and other 

 hues, not excepting greenish. Many seemed sparsely speckled with 

 whitish tubercles. In all the back was the darker surface. 



These creatures feed readily on animal substances, also on the muci- 

 laginous softer parts of decaying vegetables. In a state of repletion, 

 the distribution of the interanea, somewhat lower than the second ven- 

 tral pore, becomes visible. The aperture for protrusion of the proboscis, 

 is a little higher. The margin of the body, both here and in several 

 other species, remains always transparent, thus denoting extraordinary 

 delicacy of the vessels if any pervade it. 



Among the favourite substances most accessible, is the snow-white 

 pupa, dwelling in the same place with the Planarise. Of this they are so 

 greedy, as actually to devour it alive. If divested of the covering wherein 

 it reposes awaiting its metamorphosis, the creature is beset on all sides 

 by a ravenous multitude of these diminutive enemies. In vain it wrestles 

 and struggles to be free of such contemptible assailants, those which 

 apparently are incapable of protecting themselves. But the proboscis 

 of the Planaria, now a formidable weapon, sheathed in the vulnerable 

 parts of the abdomen, absorbs the softer matter, and the predacious host 

 retreat glutted with the contents, leaving only an empty skin behind, with 

 the thorax and limbs entire. 



The colour, size, and whole aspect of the animal, are materially 

 affected by the quantity and the quality of the food. One of large dimen- 

 sions, from dingy white, became slate-grey in ten days. The specimens, 

 Plate XVI., figs. 10, 11, were blackish-grey and brown. The position of 

 two eyes is very distinct in the head, enlarged, fig. 12, and they become 

 still more conspicuous when compressed between two glass plates, as 

 practised by some naturalists, fig. 13. 



