TADPOLES. 



349 



mouth by the nostrils which are supplied with valves. When in the mouth, which is closed on 

 all sides, with the exception of the throat, where are the gill or branchial slits, the water, acted upon 

 by the muscles which cover them, traverses their spaces, and bathes the branchiae, before its exit 



through the slits. 



The eyes are perfectly formed at this time, and the mouth has changed its position from 

 below to the extremity of the head. It is very small, and there are no teeth, but minute 

 horny plates are on the jaws, sufficiently strong to tear the soft animal and vegetable sub- 

 stances which form the food. The 

 Tadpole has a digestive system, 

 the stomach being succeeded by 

 an intestine which is of nearly 

 equal size throughout its length, 

 which is great. It is at least 

 ten times as long as the inside 

 of the body, and is curled up in 

 a coil, and it occupies most of the 

 abdominal cavity. During the 

 growth of the Tadpole, and its 

 change into the perfect Frog or 

 Toad, it becomes shorter in pro- 

 portion to the length of the 

 animal, until at last it is not 

 one-quarter of its original length. 



The tail soon becomes de- 

 veloped sufficiently to move, and 

 to move its possessor, and the 

 colour of the body changes, be- 

 coming a soft olive-green instead 

 of black, the abdomen being 

 dotted with golden-yellow. The METAMORPHOSES OF FROG. 



external form thus altered re- H) Egg of Frog; f21 Egg Fecundated, and surrounded by Us Vesicle ; IS) First state of Tadpole; (4) 



Appearance of Breathing Gi Us ; (ft) Stage with Internal Gill,; (6) Formation of Hind Feet; (7) 

 mains for SOme time and the Formati"ni>f ForeFeet and Decay of Gills; (8) Development of Lungs and Reduction of Tail; (9) 



rudiments of the hind limbs 



appear, the toes budding at their extremities. Soon the fore limbs do the same. Then, as 

 the hinder limbs increase, the tail is removed by absorption, which begins at the tip. When the 

 branchiae have ceased their function, and lungs have developed, the creature is tail-less, and having 

 long hind legs, comes to land, for it has become capable of respiring air with its lungs, and of 

 hopping and jumping to search after small insects and worms. As growth proceeds, the webs to 

 the digits, barely visible at first, become important structures, and the colour, glands, and ornamenta- 

 tion of the skin are noticed. Such multitudes, writes Bell, have been found in damp weather as to 

 have given rise to many a story of its having rained Frogs. They now grow rapidly, until the 

 approach of winter causes them to seek a retreat for hibernation. Bell states that so numerous are 

 the enemies of the Tadpoles and young Frogs in the form of birds, fish, reptiles, and the smaller 

 carnivora, that not one in a thousand survives. It is some time before the adult condition is 

 reached, for Batrachia grow for several years, and then may be said to be perfect. 



THE AGLOSSA (THE BATRACHIANS WITHOUT TONGUES). 



The first sub-order of the Anoura contains those which have not a tongue. They are large, flat, 

 ugly creatures with the eyes placed far forwards and close to the sides of the mouth, and their 

 tympanum is concealed. All have the hind feet with a perfect web between the toes, and they live 

 in hot countries, having a remarkable geographical distribution. There are three families of them. 



The Surinam Toad, which was first noticed by Sibylla von Merian, in 1708, and which is 

 a flat toad-like creature with a short, broad, and pointed head, huge hind limbs with webbed 

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