GEOLOGICAL. 201 



sculptured flinty plate beneath. When irritated or ex- 

 cited, just as a body of infantry kneel to receive a charge 

 of cavalry with fixed bayonets, or a hedgehog to receive 

 a dog, or a porcupine to defend itself from an enemy ; so, 

 over the whole surface of the body of a synapta, these 

 sharp-pointed flukes of the anchor-shaped spines are made 

 to project, upon the extremities of which the adversary 

 becomes impaled. 



Who would have thought that the mineral with which 

 we are so familiar, and which, in the form of a pebble, we 

 so often thoughtlessly kick on the roadside, or shovel up 

 in minute atoms on the sea-shore in the form of sand, 

 could, by the slow process of nature, bo wrought into such 

 lovely forms as those we see in the skeletons of plants or 

 the spicules of a sponge ? 



Sometimes the thickness of a sponge may not be more 

 than the paper which forms the page upon which this 

 is printed, and yet there is room and to spare for 

 these siliceous armouries, in which a small worm, en- 

 tangled amidst such deadly instruments, would struggle 

 in vain. 



It may be, and I believe is, that the anchor-shaped 

 spines of the synapta are intended for such a purpose, 

 serving, not only for prehension, but protection. Here is 

 a specimen in which the flukes of the anchor are serrated, 

 thus giving it a firmer hold. Some years ago I was 

 showing these spines to a mechanical friend, who had 

 taken out a patent for a new anchor, and when he saw 

 the object now under our glass he angrily exclaimed, 

 " Why, somebody has infringed ray patent, and has 

 actually copied my design ! " 



Now, when you use your sponge, will you think of the 

 romantic story this curious family could tell, both in the 

 long dim ages of the past, and in the more lively chapters 



