184 ZOOLOGY. 



sacs resting against the sides of the body; when the animal 

 leaves the water they are absorbed, leaving a scar (Fig. 230). 

 Sij)honops Mexicana is a Mexican form. 



Order 5. Anura (Toads and Frogs). — These are the tail- 

 less Batrachians. Frogs either live in or by the edge of 

 pools and brooks, and when attacked on land they can by 

 vigorous leaps escape to a place of safety. Unlike other 

 Amphibians, they are powerful leapers, the legs being mus- 

 cular, and their toes very long. The lower jaw is usually 

 toothless. The larva? are called tadpoles, and represent 

 the permanent, adult form of the salamanders. The 

 mouth of tadpoles (Fig. 225, ^4) is small, almost minute, 

 the lips armed with horny plates. They nibble dead leaves, 

 while the mature animal has a very large mouth with teeth, 

 and is carnivorous. The transformation of form of the 

 mouth and digestive organs is as remarkable as in the but- 

 terfly. 



Among the lower frogs are certain tropical forms, as 

 Alytes, Pelobates, and Pelodytes, whose breeding habits are 

 peculiar and interesting. The eggs of Pelodytes are de- 

 posited in small clusters in the water, those of Pelobates in 

 a thick loop. The male of the European Alytes obstetricans 

 winds a string of eggs which it takes from the female, and 

 goes into the water, where it remains until the young 

 (which have no gills) are hatched. The American Scaph- 

 iopus, or spade-footed toad, is not known to have this 

 habit. This singular toad appears suddenly and in great 

 numbers. It remains but a day or two in the water, where 

 it lays its eggs in bunches from one to three inches in di- 

 ameter. The tadpoles hatch in about six days after the 

 eggs are laid; their growth is rapid, the young toads leav- 

 ing the water in two or three weeks. The croaking of this 

 toad is harsh, peculiar, and need not be confounded with 

 that of any other species. As the spade-footed toads are 

 rarely seen, it is possible that they burrow in the soil, like 

 the European Alytes. Another peculiarity in the habits 

 of Alytes, Pelobates, Cultripcs, and Pelodytes is that they 



