366 



that's it ; 



in almost every part. After the complete for- 

 mation of gills, they begin to be gradually 

 absorbed, while the formation of true lungs is 

 going on, until at length, towards the end of 

 the autumn, it is an air-breathing reptile, and 

 no longer a fish.* 



The tadpole, 2, is the young of 

 the frog, and undergoes similar 



1196. 



transformations to those referred 

 to as occurring with the newt. 



When the tadpoles are first 

 hatched, they are furnished with 

 small brai\chice, 3, on either side 

 of the head, which, as well as 

 serving as gills, enable the little 

 creatures to lay hold of any object 

 upon which they wish to rest. 

 These branchiae speedily enlarge, 

 and each of the two branches on 

 either side is seen to consist of 

 about four leaves, 4 ; but the 

 head rapidly enlarges, and the 

 branchiae are gradually included 

 in the cavity of the chest, 5, 

 until they altogether disappear. 

 The eyes are now perfectly 

 formed, the mouth has acquired 

 moveable lips, and the little 

 creature now seeks its food amid 

 softened and decomposing vege- 

 table matter. The tail has become 

 highly developed, and serves for 

 rapid locomotion, 6. 



* 3 w rl>y's i'uuulur History of the Aquarium 



The tadpole now undergoes 

 but little change in its external 

 form for a considerable time, but 

 increases rapidly in bulk, and 

 by-and-by a little tubercle appears 

 on each side of the tail ; these 

 soon acquire the form of perfect 

 limbs, the toes budding at the 

 extremities ; and a similar pro- 

 cess occurs with the anterior 

 members, 7. As the legs are 

 developed, the tail is removed by 

 absorption, which begins at the 

 apex, and progresses onwards to 

 the base, and finally the whole 

 is absorbed, 8, and the posterior 

 part of the body becomes rounded. 



Among the busy creatures of 

 ponds, will be found the boat-fly, 

 9, the back of which is shaped 

 like the bottom of a 9 

 boat, and the hind- 

 legs, which are nearly 

 three times as long 

 as the front ones, are 

 used as a pair of oars. 

 The legs of the hinder 

 pair have a fringe of 119 ". 

 bristles along their edge, by 

 which the surface that strikes 

 the water in swimming is greatly 

 increased. They swim on their 

 backs, and their eyes are so 

 placed, that they are able to see 

 both above and below the surface 

 of the water, so that at the 

 approach of danger they instantly 

 descend, and are out of sight. 



The larva of the ephemera, 10, 

 or day-fly, is one of the most 

 interesting objects of the aquatic 

 world. The name of ephemera, 

 or day-fly, has been given to it, 

 in consequence of the very short 

 duration of life of the insect when 

 arrived at a perfect state. But 



