11 



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 the species, 

 and even the higher assemblages of forms, often pass so in- 

 sensibly 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, we find the two kingdoms so 

 closely connected, that there are instances of the same forms 

 having been regarded, first as animals, and afterwards as 

 vegetables, or the contrary. There are some mammals allied 

 to reptiles in certain parts of their internal organization, 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 the 

 ornithic structure; — there is the Lepidosiren, so completely 

 intermediate between reptile and fish, as to have led to a con- 

 troversy 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, only recently discovered — the 

 Archceopteryx, 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 exhibiting 

 characters which separate it from all birds known hitherto, it 

 having a long vertebrate tail, and apparently other characters 

 equally exceptional, but which are not at present capable of 

 being defined with accuracy, from the imperfect state of the 

 remains of the only specimen hitherto examined. 



The above remarks are in reference to the vertebrate division 

 of animals; but they apply equally to the invertebrate, the 

 several classes of which seem in like manner to be all con- 

 nected by osculant forms, while there is a genus of fishes, — 

 the Amphioxus of Yarrel found on our own shores, — so low in its 

 organization, and with the vertebral column so imperfectly 

 developed, as to present more the appearance of a mollusk 

 than a fish, and actually to have been classed with the 

 mollusca by one naturalist (the celebrated Pallas) ; thus 

 shewing that even the two great divisions of Vertebrata and 

 Invertebratahave no such clearly-defined boundary between them 

 as might have been supposed.* We know yet further the bold 

 hypothesis of one of the most philosophical naturalists of our 

 day, — not entirely unsupported by facts, nay with a large 

 body of facts in its favour, though certainly not proved, nor 



* The above remark applies to outward form alone, for there is no doubt 

 as to the Amphioxus, in internal structui'e, being a true Vertebrate. 



