FROGS. 31 



black, and usually marked with aggregate spots or blotches some- 

 what like the green-frog tadpole. In the pickerel-frog and leopard- 

 frog tadpoles, in spite of the coppery iridescence on the belly, the 

 elongate intestine shows through the skin, while in the green-frog 

 tadpole the deep cream color hides the view of the intestine. The 

 pickerel-frog tadpoles never reach 3 inches in length. (See PL XX, 

 fig. 6.) 



The green-fro^ tadpole requires one year for gi'owth before it 

 becomes a small fully formed frog. The same factors operate for this 

 extension of time as in the case of the bullfrog tadpole. The tadpole 

 of the green frog, however, has to attain a size slightly more tlian 

 one-half that of the mature bullfrog tadpole, and the larval or tadpole 

 period is, therefore, one-half as long. The distinctive marks are: 

 Tail gi-eenish, mottled with brown; belly deep cream color with very 

 little or no iridescence; no round black spots; never over S^ inches 

 in length. (See PL XX, figs. 5 and 7.) 



The bullfrog tadpole requires two years or more for growth be- 

 fore it transforms or becomes a frog in form. This long period of 

 development results from several causes, among which are these: 

 The eggs are relatively small and are laid late in the season; and 

 the larvfB or tadpoles are hatched in an immature state and have 

 to grow to a comparatively large size before they change into small 

 bullfrogs; that is, the mature bullfrog tadpole may be three times 

 as long as a wood-frog tadpole or twice that of a pickerel-frog or 

 leopard -frog tadpole. Any tadpole over 3^^ inches in length will 

 prove to be that of a bullfrog. The distinctive marks are: Belly of 

 a straw or maize yellow color; the body and the tail (except the 

 lower crest of fin) with regular round black spots; and fine yellow 

 dots all over the body. (See PL XX, fi^s, 1, 2, and 3.) 



Possible Species. — With the exception of the toad, the tadpoles 

 of several possible forms are not well enough known to describe posi- 

 tively. The toad tadpoles seldom reach more than from 1 to 1^ 

 inches in length. The small size required enables the tadpole to 

 develop quickly into the toad form. The period of development 

 from the egg to transformation is from 50 to 65 days; from the hatch- 

 ing to transformation, 41 to 60 days. The distinctive marks of the 

 tadpole are : Body very dark or black (not greenish) in appearance ; 

 crests of the tail cloudy transparent or milky translucent and not 

 high ; tail tip often more or less rounded . (See PL XX, fig. 11.) 



The tadpole of the wood frog develops in one season; usually the 

 period of development from the eggs to transformation extends over 

 about 90 days, though the range may be from 61 to 115 days. The 

 tadpole period and breeding time of the wood frog coincide with 

 those of the leopard frog. The tadpole of the wood frog never 

 becomes more than 2 inches long. Like that of the leopard frog the 

 belly of the wood frog has a bronzy iridescence, but it is more pinkish 

 in the latter along the upper-jav/ region, while the wood-frog tadpole 

 has a cream-colored line; finally, the mouth of the tadpole of the 

 wood frog has three rows of teeth on the upper jaw and four rows on 

 the lower jaw, while all the desirable species have two rows of teeth 

 on the upper jaw and three on the lower. (See PL XX, fig. 10.) 

 • Undesirable Species. — Some of the more frequent tadpoles 

 which should be avoided are those of the narrow-mouthed toad, the 

 tree toad, the peeper, the swamp cricket frog, and the cricket frog. 



