30 PLANARIA NIGRA. 



or straw selected for the deposit, or the 

 side of the including vessel. It is of a per- 

 fect oval figure, of a dark brown or choco- 

 late colour, provided with a hard shell, and 

 in every respect exactly resembles a bird's 

 egg in miniature. Those of the largest 

 size, for great inequalities prevail, are about 

 a tenth of an inch long ; and one of this 

 description is seen, somewhat magnified, 

 Fig. 4. I cannot confidently affirm that 

 more than a single egg is produced by each 

 planar ia ; but each egg contains several 

 young, of the palest grey, or almost white : 

 their anatomical structure is then best dis- 

 closed, as they speedily darken by succeed- 

 ing increment. Some, hatched in the se- 

 cond week of September, were deep grey 

 on the fourth of October. The specks or 

 eyes may be recognized at an early stage, 

 by a magnifier, Fig. 5. which also exposes 

 slight discrepancies in shape, between the 

 young and the adult animal. A consider- 

 able interval elapses before exclusion of the 

 young planaria ; but observations on the 



