SANGUINE SPONGE. 261 



its general clearness. If touched, it does not shrink 

 at once, but if we remove the specimen from the 

 water, and presently replace it, we find the tube so 

 shrivelled as to be invisible ; though by patiently 

 watching for a few minutes, we perceive it slowly re- 

 appearing, minute at first, and closed at the extremity, 

 but soon acquiring its former dimensions, and gradu- 

 ally opening it's terminal orifice. 



We have, however, found other kinds of Sponge 

 besides these at our rocky point. Now it frequently 

 happens in natural history that, though endowments, 

 and faculties, and properties are common to 'several 

 allied species, some one of these is observed to most 

 advantage in one species, and some in another. This 

 projection of delicate gelatinous tubes, a highly curious 

 and interesting phenomenon to witness, for example, 

 is better shown by the low vermillion crust of the 

 Sanguine Sponge, than by the mammillary hillocks 

 of the Koseate sort. This is a very common species, 

 and one which, by its scattered patches of brilliant 

 scarlet, much assists to give that rich variety of colour 

 which our rocks display when exposed at the lowest 

 spring-tides. Examining, then, our specimen of this 

 beautiful Sponge, with the same appliances and the 

 same care as we used for the others, we obtain the 

 following results. 



I may compare the Sanguine Sponge to an uneven, 

 rather than a hilly country, the eminences being uni- 

 formly lower, and very irregular in shape and elevation. 

 Perforations appear here and there, like deep round 



