SPONGES, ZOOPHYTES, AND SEA-FIRS. 39 



A smaller but much more dainty little sponge is Grantia 

 ciliata, a delicate silky little creature not usually more than 

 half an inch in length. It is oval in form, of a cream or 

 greyish colour, and has a crown of beautiful spicules round 

 the osculum. It is a solitary form and usually occurs far 

 out on the rocks. When examined with a lens it will be 

 seen that the silky appearance is due to the fact that the 

 surface is covered with prominences, each ending in a long 

 slender spicule. In life the direction of the crown of 

 spicules varies according to the flow of water through the 

 sponge; sometimes they spread outwards in a radiating 

 manner, and at other times they lie parallel to the long 

 axis of the sponge. This pretty little sponge is not very 

 common on the shore, and usually requires to be sought for. 



These three examples may serve to give the student some 

 idea of sponge structure ; on certain parts of the coast, 

 especially on the South, other species are common between 

 tide-marks, but for these reference must be made to special 

 memoirs. 



After the sponges we come to the hollow-bodied animals, 

 or Coelentera, which include some of the most beautiful of 

 our shore animals. Lovely as they are in life, both in 

 colour and form, they lose practically all their beauty at 

 death, when the majority become mere shapeless masses. 

 In consequence they must be studied in the living con- 

 dition, and this is fortunately rendered possible by the fact 

 that not a few will live well in confinement. This is, of 

 course, especially true of the sea-anemones, which make 

 charming pets. A few words may be said as to the best 

 methods of keeping the more delicate sea animals alive. 

 Those who have abundance of spare time, much patience, 

 and not a little spare cash will probably take naturally to 

 aquarium-keeping that is, to the maintenance of tanks con- 

 taining sufficient growing plants to balance the animal life. 

 Even when all these requisites are present, however, the 

 aquarium is always liable to go wrong, and is never very 

 easy of management except on a very small scale. By far 

 the easiest method of keeping marine animals alive is in 

 flat shallow pans, which expose a large surface to the air 

 relative to the bulk of water present. A common pie-dish 

 of large size does well. It should only be about half full, 



