108 PLANARIA. 



is none of which I was longer disappointed of finding specimens, year after 

 year, yet always unsuccessfully, and only in two places has it hitherto 

 occurred to me. One of these is Philipston Loch, twelve miles west of 

 the City of Edinburgh ; the other, a pond in Red Braes garden, within 

 a mile of this our northern metropolis. There it dwells in the greatest 

 profusion. 



Full-grown specimens extend nine lines, by nearly a line and a half 

 in breadth. Body almost linear, with the front even, and posterior ex- 

 tremity rather acute ; slightly convex above in repletion, and flattened 

 in abstinence. Naturalists assign two black eyes to this species towards 

 the anterior margin of the upper surface. In two subjected to the micro- 

 scope, I found four eyes, two larger towards the angles of the head, and 

 a black speck, not a fourth part as large, in front of each. The natural 

 colour of the animal, which can be discovered only when it is in a state 

 of abstinence, is pure white. This is affected by every kind of food. 

 Plate XVI. fig. 5. 



But when replete with sustenance, whether red or dark, the curious 

 and beautiful arrangement of the interanea is displayed. The food is ab- 

 sorbed by a proboscis, the site of which, and that of the stomach, are de- 

 noted by a clearer elliptical portion in the centre of the under surface, pro- 

 longed downwards. Almost the whole body is occupied by fine pinnate in- 

 teranea, being so many caeca, as I conclude, distributed from around these 

 organs, and reaching to the marginal belt. Plate XV. fig. 4. The form 

 of these internal organs will be better understood from an accurate en- 

 larged view of a specimen. The upper and under portion are represented 

 on a scale still larger, figs. 5, 6. 



I cannot speak positively of the propagation of this Planaria. Dr 

 James Rawlins Johnson, a very acute naturalist, sent me along with a 

 number of preparations of various Planariae, what he considered the 

 ovum. About fifteen years ago I procured a fine specimen, and next 

 day observed the ovum, Plate XVI. fig. 9, on a leaf in the vessel, on 

 July 3. It was a perfect ellipsoid, of a brownish colour. But I was dis- 

 appointed' of progeny. I have had at least 500 of these animals taken 

 at different seasons of the year, and still none were prolific ; therefore, if 



