multitude of polyps, the whole, as Professor Ansted expresses it, "constituting a kind of compound animal, in which each individual works to increase the general mass, and is affected by that which affects this mass; but each, also, has a separate existence, being provided with a stomach and arms, to obtain and digest food, and capable of being injured or destroyed without the functions of the complete body being at all interfered with."

Among the corallines or small corals, the most beautiful organic remains belong to those called Aulopora and Catenipora. The first, which is simple and flower-like, is common among the oldest fossiliferous rocks, and closely resembles many species which are yet found in the southern and tropical seas. The other kind, which is popularly called the chain coral, is extremely common among the rocks at Dudley and other silurian localities.

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The Trilobites were very curious crustaceous animals. "These," Professor Ansted observes, provided with a large semicircular or crescent-shaped shield, completely defending the head; the body was in like manner secured from the attack of an enemy, by a number of plates or segments moving readily upon one another, like the horny plates of a shrimp; and the tail was armed with a similar series. The animal seems not to have had antennæ, and to have possessed short and rudimentary legs; but on the head were placed a pair of large conical projections covered with eyes, by the help of which any approaching danger might be seen; and the power of rolling itself into a ball, which it possessed in common with the wood-louse and the chiton, enabled this creature,

no doubt, to escape the attack of many of its enemies. It is not very easy either to make out the habits of an animal of such singular organization and of which only the hard external coat is preserved, or to speculate with regard to its food, and its method of obtaining it. From the absence of antennæ, however, and the want of powerful extremities, as well as from the manner in which these fossils are found (for they seem to have been very gregarious, living by thousands in a single locality, and often heaped upon one another), the different species probably lived for the most part in shallow water, not buried in mud, but floating near the surface with their under side uppermost, feeding on the minute and perhaps microscopic animalcules that usually abound in such localities. There are several natural groups, marked by differences somewhat considerable, but the number of species is not great. The most remarkable point with regard to these trilobites is the presence of the large compound eyes with which they were provided. These eyes appear to be constructed on the same principle as those of the dragon-fly and other insects: they are ranged round about three-fourths of two conical projections rising one from each side of the head, and they are so placed that the animal, without moving from the spot in which it might be, could see in all directions around it." The trilobites are found in the greatest abundance at Dudley and its vicinity.

Among the shells the most interesting are what are called the Ammonites, or the shell of an animal somewhat similar to the Nautilus, but having a connecting siphon on the outside, instead of within. The

Belemnite "has received its name," says Professor Ansted, "from a peculiar dart-shaped stony fossil, and which, under various local names, such as the thunderbolt, &c., is familiar to most people in the different parts of England where it occurs abundantly. It is found varying in size from specimens not an inch long, to others measuring upwards of a foot; but the structure is generally seen to be the same, the fossil when complete being more or less cylindrical, with one conical extremity, the other end widening out and exhibiting a conical hollow, which is sometimes filled up with a number of little cupshaped bodies like watch-glasses, fitting into one another." Naturalists were long puzzled with regard to this fossil, but its history is now perfectly cleared up "by the aid of specimens which not only exhibit all the solid parts in their natural position, but even present to our notice the muscular fibre, very little altered. The whole contour of the animal is, indeed, accurately determined, including the feelers projecting from the head, the fins, the tail, and even a solidified dark fluid once preserved within the body, and intended to serve the living animal as a defence from its enemies, by enabling it to cloud the surrounding water when attacked or desirous of concealment." The fossil known to geologists by the name of Belemnite is the internal skeleton of an animal very much like the cuttle-fish, but provided, not only with a solid framework for the attachment of muscles, but also with an apparatus like that possessed by the Nautilus and the Ammonite. The animal of the Belemnite was enclosed within a muscular shape, which formed a kind of closed bag termina

M

ting above with the head. "From around this eight arms proceeded, whose length in the species examined seems to be about one-fourth part of the entire length of the animal; and each arm was provided with from fifteen to twenty pairs of hooks, resembling those now seen only in the most powerful and the fiercest of the whole tribe of Cephalopoda, and used to pierce the flesh of fishes and other animals, in order to secure firm hold when the Belemnite was about to seize its prey. The head was provided with very large eyes; the jaws were probably horny; and, besides the eight arms, there seems to have been one pair of long tentacles. Far down below the head, and within the cavity of the shell, there was placed an oval sac containing a black fluid, communicating by a tube with the aperture. This fluid exactly resembles the ink of the common cuttle-fish; and there can be no doubt that it was used by the animal in the same way, and for the same purpose, namely, to darken the water when its possessor, becoming alarmed, desired to escape. The ink itself in a solid state, the bag which contained it, and the tube or pen by which it was shot out into the water, are all preserved in some of the specimens of this fossil. The mantle of the Belemnite, passing over the guard or shell, seems to have accommodated itself to the shape of the shell, and terminated in a blunt point. Two fins, however, of a rounded form, and of considerable size, extended on each side near the middle of the animal. From this position of the fins, from the shape of the shell, and from its general structure, it has been concluded that the animal commonly remained in a vertical position, rising and sinking with great

facility, and possessing very unusual powers of locomotion and destruction."

CHAPTER VII.

EARTHQUAKES.

AFTER speaking of the wonders which are found on the surface of the earth, and in its recesses, it now seems natural to say a few words on those violent convulsions of nature, which appear occasionally to shake it to its centre, and to effect the most extraordinary changes in its outward appearance. There appears but little doubt that earthquakes are intimately connected with volcanoes, though it is very difficult to understand how the subterraneous vapours which occasion them are generated, and in what way they gain sufficient force, to produce the extraordinary effects which we see result from them, at such a great depth from the surface of the ground. In the great earthquake which took place in Asia Minor in the seventeenth year of the Christian era, and which destroyed thirteen great cities in one night, and shook a mass of earth 300 miles in diameter, it has been calculated that the moving power, supposing it to have been internal fire or vapour, must have been launched 200 miles below the surface of the earth.

Another great earthquake destroyed the city of Antioch. Another threw down the famous Colossus of Rhodes. In more modern times, we find descriptions of the earthquake at Puteoli, which occasioned the sea to retire 200 yards from its former bed; the earth