TERRARIA AND AQUA-TERRARIA 



assumes either an ovoid or a lozenge form. Dependent upon the tem- 

 perature of the water and the different species, the period of incubation 

 may be from 6 to 30 days. When the tadpole wriggles out of the 

 gelatinous cover, which serves as its first food consumed by absorption, 

 the mouth and anus soon become functionary, the alimentary canal elon- 

 gates, and the tadpole begins to feed on macerated vegetal and animal 

 matter. At first respiration takes place by external gills, but these are 

 soon replaced by internal structures covered by operculag. The rapidity 

 of development depends upon natural conditions and in the different 

 species may be in 3 months to 2 years. The first indication of the meta- 

 morphosis is in the development of the hind legs, then the fore-legs de- 

 velop under the gill membranes, and finally the tail is absorbed, at which 

 period the gills are replaced by lungs and the young frog or toad becomes 

 amphibious. The food is no longer organic matter but living organisms, 

 and its usefulness as an aquarium scavenger ceases. 



Tadpoles of the toad may be distinguished from those of the frog by 

 their blacker color, the latter being preferable in the aquarium, as they are 

 better scavengers and remain longer in the tadpole stage. 



Frogs. These have long and tapering tongues fastened to the front 

 of the mouth, free behind, and the tip pointing down the throat. Their 

 prey is taken by its quick protrusion, and the adhesion to its viscid cov- 

 ering. Maturity is reached by the toad in one season, but with some of 

 the frogs it is delayed for 2 or 3 years ; while tadpoles in aquaria some- 

 times never undergo the final metamorphosis, probably due to the en- 

 forced aquatic conditions. In the United States there are 13 recognized 

 species and 6 sub-species of frogs ; those most generally distributed being 

 the Spring or Leopard Frog, the Green Frog, the Common Bullfrog, the 

 Western Frog and the Western Bullfrog. 



Rana virescens, (Shaw), the Spring or Leopard Frog, is found from 

 the Atlantic Coast to the Sierra Nevada Mountains and from Lake Ath- 

 abasca to Central America, but is most abundant in the Eastern States. 

 It grows to a length of 3 i^ inches, exclusive of the legs ; has a rather 

 pointed snout, and the tympanum of the male is nearly as large as the 

 eye. The color is bright green marked with olive, with dark-brown and 

 black blotches in two irregular rows on the back, and one or more indefi- 

 nite rows on the sides. The yellow glandular fold, which is a distinguish- 

 ing characteristic in the different species, reaches from the orbit to the 

 posterior end of the body. This frog passes through the tadpole stages 

 in one season and its cry may be defined by the syllables cluck cluck; cluck 

 cluck in gutteral tones. 



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