20 NATURAL HISTORY OF OUR SHORES 



surface. So diverse is the growth that, apart from micro- 

 scopical examination, the species is often difficult to de- 

 termine. 



It thrives best about the middle zone of tide range, be- 

 coming scarce as the limits of both high and low water 

 are reached. In favourable situations it forms large 



Fig. 7. Halichondria panicea. Natural size 



masses, often covering several square feet, and varies in 

 thickness from half -an -inch to two or three inches. In 

 Fig. 7 it is photographed in its actual size as regards 

 osculse, etc. 



In the same localities as this species grows are also found 

 very abundantly large patches of the orange and crimson 

 Hymeniacidon, and sometimes some of the branching 

 forms, Isodictya and Chalina. These grow in the form of 



