GEOLOGICAL. 195 



Vessels ! Can anything be truly said to be " lost," after 

 this? 



One of my friends once showed me the ball from the 

 socket of one of the mighty limbs of the gigantic 

 mastodon, one of those prehistoric animals which, ages 

 since, inhabited our dear England long before the advent 

 of our Druid or Saxon ancestors. It was found in the 

 Thames, and was supposed to have fallen in while the 

 embankment at Westminster was making; it measured 

 thirty-eight inches in circumference, and weighed forty- 

 one pounds. 



These interesting remains of an antediluvian epoch, 

 which have been discovered from time to time in and 

 near London, have received an addition in the fossilized 

 bones of a whale in my own immediate neighbourhood, 

 at Greenwich, while they were excavating for the railway 

 there. The remains, which consisted of part of the 

 vertebra and jawbone, were lying in the gravel, and were 

 in a fair state of preservation. 



Having directed your thoughts to similar objects, 

 connected more or less with microscopical studies, in 

 previous works, I must not occupy either time or space 

 in repetition ; but I would here call your attention, very 

 briefly, to the great family of sponges, both recent and 

 fossil, for you will find that in the latter state, both in 

 their vertical and horizontal sections (several beautifully 

 prepared specimens of which await our examination), 

 that the skeleton is seen perfectly much more so, indeed, 

 than in a living sponge but entirely filled up with silica, 

 which being transparent when cut down to a minimum of 

 thinness, the network of the skeleton is clearly seen 

 through. 



We must not suppose that these phenomena are 

 confined either to the surface of our earth or to our own 



