70 FAMILY OF ANOURA. 



same time, the horny beak falls off, leaving the 

 jaws unencumbered ; the tail begins to waste 

 away, (Fig. 34.) the lungs are developed, and, 

 in proportion as these organs become more ex- 

 clusively the seat of respiration, the branchise 

 fade and disappear; the cartilaginous arches 

 which supported them are also in part absorbed ; 

 Fig, 35. arj d finally the tail entirely disappears. The 

 little animal assumes the form which it preserves 

 through life, and completely changes its regimen, 

 (Fi(j. 35.) From being at first herbivorous, it 

 gradually becomes exclusively carnivorous, and 

 in proportion as this- metamorphosis advances, 

 FROG. the intestinal canal, from being long, slender, and 



spirally folded, becomes short, almost straight and swelled, to 



form the stomach and colon. 



7. The period of these changes varies, from about four to eight 

 weeks, according to the species, and it has been ascertained that 

 different circumstances may considerably hasten or retard, the 

 complete metamorphosis of the young animal. A deficiency of 

 heat and light, very much prolongs the duration of the tadpole 

 state. 



8. Having reached their perfect state, the Anoura cease to be 

 aquatic animals; but most of them continue to live in the neigh- 

 bourhood of water and dive frequently in it. They cannot remain, 

 during the warm season, constantly in the water, even though 

 they come freely to the surface to breathe the air ; pulmonary 

 respiration is not then sufficient for them, and they require the 

 action of the air on the skin ; in winter, however, this cutaneous 

 respiration is not only sufficient to sustain life, but they can 

 remain several months in the water without coming into the air. 



9. All these reptiles have a thick-set body, a flat head, the 

 muzzle more or less rounded, a very wide mouth, short fore feet 

 terminated by four toes, and the hind feet are longer, and some- 

 times possess the rudiment of a sixth toe. Their eyes are ordi- 

 narily furnished with three lids, but sink into the head, on slight 

 pressure; because the orbits art separated from the mouth only 

 by membranes. A cartilaginous plate occupies the place of a 

 tympanum, and causes the ear to show externally. The tongue 



7. Is the time occupied in these changes the same in all species of Anoura? 

 What circumstance influences the time occupied in the metamorphosis ? 



8. What are the habits of the Anoura? Is respiration carried on exclu- 

 sively by the lungs ? 



9. What are the general characters of the Anoura ? How do they breathe ? 

 What is peculiar about the tongue? 



