u 



With the Physical Sciences this Chib has nothing to do. But 

 confining ourselves to the Natural Sciences, all who attend much 

 to them must be struck with the mutual bearing they have on 

 each other. From Mineralogy, already spoken of, there is an easy 

 passage to Geology. But Geology is entirely dependent upon 

 zoology for ascertaining the true characters and structure of those 

 fossil organic forms, which abound more or less in all rocks and 

 strata from the highest nearly to the lowest, and which lielp 

 mainly to determine the relative ages of that succession of beds 

 which form the crust of our earth. With respect to the affinities 

 existing between the several classes of animals, as also between 

 the several families of plants, — and what is yet more between 

 plants and animals themselves, — it is enough to say that tlie 

 species, and even the higher assemblages of forms, often pass so 

 insensibly into each other, that it is hardly possible to determine 

 where one group ends and another begins ; and when we come 

 down to the lowest forms of all, Ave find the two kingdoms so 

 closely connected, that there are instances of the same forms 

 having been regarded, first as animals, and afterwards as veget- 

 ables, or the contrary. There are some mammals allied to 

 reptiles in certain parts of their internal organisation, others 

 taking much after the form of fish and allied to them in habits ; 

 — there are birds possessing some of the characters of mammals, 

 and departing considerably from the ordinary type of tiie ornithic 

 structure ; — there is the Lepldodren, so completely intermediate 

 between reptile and fish, as to have led to a controversy among 

 naturalists as to the class to which it really belongs, and, joined 

 with other considerations, to have induced one of our first 

 authorities, Professor Owen, to propose the actual uniting of these 

 two classes, on the ground of their having so many characters in 

 common. Lastly, there is that most extraordinary fossil form, 

 «nly recently discovered — tl.'e Ardueoptcryx, from the Solenhofen 

 beds of Pappenheim — at first considered by Wagner as a feathered 

 reptile, but now thought by Professor Owen to be a bird, though 



