AND THE LOWER ANIMALS. 87 



CHAPTER IX. 



METAMOBPHOSES OF BATEACHIA AND LAMPREYS. 



In treating of insects, we entered, as was necessary, 

 into some detail. Their metamorphoses form, as it 

 were, a key to the study of these phenomena gene- 

 rally. Besides, the terms caterpillar, chrysalis, butterfly, 

 worm, beetle, and grasshopper, recall to our readers' 

 minds certain familiar objects. Whilst following us 

 through this land of wonders, readers have been meet- 

 ing old acquaintances; and thanks to these, it is 

 hoped that they have grasped the anatomical facts and 

 physiological generalizations, which are more foreign 

 to their usual occupations than the other portion of 

 our remarks. We must now retrace our steps, and 

 from the same point of view explore the whole animal 

 kingdom. Consequently we must enter regions much 

 less known to the general reader. In order that we 

 may be easily understood, we shall be brief, and shall 

 henceforth confine ourselves to pointing out those 

 important facts from which general conclusions may 

 be drawn. 



In the very outset we come upon a group with 

 which every one is acquainted, and which deserves 

 special attention, from the fact that for a long while 

 it had been considered as the only vertebrate class 

 exhibiting metamorphoses. We allude to Batrachia, 

 including frogs, land and water newts, and the 



