21 



slender stems, about the thickness of a pencil, and they 

 creep over the surface of the rock, often crossing, and 

 coalescing in the form of lattice -work. Their colour varies 

 from pale yellow through orange, red, crimson to deep 

 purple, but these are more abundant at a lower zone. 



Fig. 8 shows a branching sponge, Isodictya palmata. 



At all ranges of the tide, where there is shelter, under 



Fig. 8. Isodictya palmata. % Natural size 



overhanging rocks, and also among the corallines in the 

 pools, will be found the little tassel-like, or rather catkin- 

 like, Sycandra ciliata. This is one of the simple sponges, 

 as regards structure. Outwardly it is of the form de- 

 scribed, in size it varies from half-an-inch to two inches in 

 height. The spicules project on the whole exterior, giving 

 it a woolly appearance, while at its apex, around its 

 osculum, there is a collar formed of several rows of strong 



