68 HIDDEN BEAUTIES OF NATURE 



and a great number have taken on the shapes of 

 mushrooms and ' toadstools.' 



Now, however, the finding of the living glass 

 sponges enables us to classify these beautiful objects, 

 for they are the euplectellae of remote geological 

 ages. 



You may perhaps say, ' How about the spicules in 

 the sarcode ? ' Astonishing to say, if we take a thin 

 piece of the flint next to the * ventriculite,' and get a 

 lapidary to polish it, the microscope will show us the 

 spicules firmly embedded in the flinty envelope. We 

 have picked up hundreds of these ' ventriculites,' or 

 * flint sponges ' on the coast between Folkestone and 

 Dover. 



The beautiful choanites found on many flinty 

 beaches, as at Folkestone, Eastbourne, Sandown, etc.. 

 are varieties of the same class of sponges which lived 

 long ages ago. 



Thus we get another peep into the history and the 

 marvellous composition of our earth, and we begin to 

 understand why it is the geologist is so fascinated 

 with his work. 



There are manifold fossil forms of sponges. They 

 could even be extracted from a block of chalk with a 

 penknife. 



The Jurassic rocks of South Germany and Switzer- 

 land contain masses of fossil sponges, so that, judging 

 from these and from the quantities of silicified 

 sponges found in the chalk of France and of Eng- 

 land we are bound to infer that innumerable hosts of 



