ANNE. The chalk districts are generally barren, I think.

MRS. L.-Generally, when there is no soil above the Chalk: and you may observe it covered with flint-stones, which appear to have been washed out of the Chalk. There is every where an appearance of destruction after the Chalk was deposited; and also of a pause before the materials were deposited above it, in places where the Chalk is covered. "In general, an interval seems to have taken place between the completion of the Chalk formation, and the deposition of those which rest upon it: and the surface of the Chalk, at its junction with the Clay above it, usually bears marks of having undergone a partial destruction at that period; a bed of ruins being spread over it, chiefly of flints washed out of the mass, and the surface being worn into frequent cavities of considerable depth, filled with the same ruins. At some places the surface is remarkable for deep indentations on its surface, which, on examination, are ascertained to be furrows and cavities, apparently occasioned by the powerful action of water on the surface of the Chalk, before the Clay and Sand were laid over it.

The Chalk Strata are, I believe, by the best arrangements, considered as the last of the Secondary Strata, those above being called Floetz, or Flat, from their horizontal position, or Alluvial deposits. But the divisions are so arbitrary and uncertain, you must not attach much importance to this.

In the cliffs of Dover considerable beds of solid Flint have been found among the Chalk. In a quarry in Wiltshire a block of Chalk Stone was found sufficiently hard to be cut into slabs for chimney-pieces: this must doubtless be occasioned by the admixture of siliceous matter with the Chalk,

MAT.-I hope we shall have an opportunity of examining a Chalk district, in some of our excursions to the coast.

MRS. L.-This may be well done either at Dover, or

Beachy Head, and in many other places. No where better than in the Isle of Wight, of the Southern coast of which I can show you a section, exhibiting not only the Chalk, but the previous Strata considered in our late conversations, since I showed you a section of the Oolitic Series. It is in the neighbourhood of St. Catharine's. The upper region of the hills consists of Chalk and Marle, the second of Green-sand and the lower of Iron-sand. By the falling of these strata one over the other, a beautiful scene of confusion is exhibited, known by the name of the Undercliff. Masses of Sandstone project in picturesque crags, covered with foliage, while vast masses of Chalk have fallen over them from the beds above to the very edge of the sea, where they are seen lying on the same level with the Iron sand. Fig. 4.

SERIES OF FAMILIAR CONVERSATIONS ON THE ANIMAL KINGDOM.

CONVERSATION XXIII.

CLASS, VERTEBRATA-SUB-CLASS, REPTILES. Metamorphoses, secretions, changes of colour, organs oj sense, voice, &c.

ANNA. In our walk last evening, Mama, Papa gav us some account of reptiles. I was astonished to lear that they have not only been known to live for month without food, but that they can maintain life for a cons derable time without respiration; and, what is still mo wonderful, that they can perform various functions afte they have been deprived, not merely of the heart brain, but even of the head.

PAPA. I have not yet told you all the wonders whi

belong to this race of animals. One order of them, the batrachians, that is to say, reptiles of the frog and toad kind, have the remarkable peculiarity, to which nothing at all analagous has been observed in the warm-blooded class or in fishes, of undergoing a metamorphosis, and have in their two states, not only an altogether different external form, but also important differences in many of the great internal organs. From a round jelly-like egg proceeds the tadpole, a little black creature, with a long tail, no legs, and tufts of fibres on each side the head, which serve as gills.

HENRY.-Then tadpoles are the larvæ of frogs and

toads?

PAPA.-They are.

After a short time the head and gills are covered with a skin: in five or six weeks the hind legs make their appearance, and in about a fortnight more the fore legs: the tail soon after drops off, the gills shrink, the lungs act, and the little aquatic reptile becomes an inhabitant of the land.

it

ANNA.-Are not toads very poisonous creatures?

PAPA.-O no, my dear. The toad is a harmless animal. It is extremely ugly, it is true; and that unfortunate circumstance has excited a disgust and horror of among the generality of people; and joined to the faculty it has of emitting a juice from its pimples, has given rise to the report of its venomous properties; but I believe it is perfectly inoffensive, at least to us; for it may be held in the hand without doing the least injury; and it is the common food of many animals, such as buzzards, owls, ducks, and snakes, who, it may be supposed, would not touch it, if it were venomous. It is said, however, by those who have examined its anatomy, that it has two glands behind the ears, containing an acrid humour, which is poison to very small creatures.

HENRY. Many reptiles secrete liquor from the skin, do they not?

PAPA. Those with naked skins, as salamanders and frogs, do; they have the surface of the body always copi