Eggs. The eggs of about 15 species have not been found and the 

 eggs of 15 species have been found but not described. In all some 30 

 species need more attention paid to them. 



Relatively, the eggs of some of the smaller frogs like the robber 

 frogs or little chorus frogs are largest while the bullfrog may have 

 some of the smallest eggs. The size of the adult then does not de- 

 termine the size of the egg. The ribbed toad and robber frogs have 

 unpigmented eggs. The latter go through their whole development in 

 the egg which is laid on land. All the rest of the frogs have pigmented 

 eggs. 



In the North the egg laying season may be very short while in the 

 South some species may breed almost any month of the year. The 

 number of eggs a female may have to lay varies from 6 in the robber 

 frogs, or 100 in the little chorus frog, to 20,000 in the bullfrog. Some lay 

 single eggs on the bottom of the pond or stream. They may be at- 

 tached to vegetation or free, submerged in the water or floating. 

 Many lay floating films. Most forms in northern countries lay sub- 

 merged eggs. Some like toads have the eggs in strings or tubes of 

 jelly though one toad has them in bars of 4 or 5 eggs and another 

 lays single eggs. Others, like spadefoots, may have them in bands, 

 later cylinders, or even have the eggs on stalks of jelly. One, the 

 ribbed toad, has the eggs in a rosary string. Some, like wood frogs 

 and meadow frogs, have globular or plinthlike masses. 



The egg proper, or yolk, is called the vitellus, which usually has a 

 rather tight fitting membrane called the vitelline membrane. The 

 vitellus usually has the upper half or animal pole pigmented black, 

 brown, etc., while the lower half or vegetable pole is unpigmented, 

 white, cream, or yellowish. These pigmented eggs are normal to most 

 frogs which lay their eggs in water exposed to the sunlight, but a few 

 frogs in the United States lay their eggs on land and away from the 

 sunlight. Such are unpigmented. About the egg there may be one or 

 two or more jelly envelopes which become evident a few minutes 

 after the egg is laid. In some masses of eggs the outer envelope loses 

 its distinctness. Sometimes the eggs are in tubes of jelly as in the toads. 



Some, like peepers, lay each single egg separately while others lay 

 several single eggs at one time. Some surface films represent the 

 moving about of the female (like tree toad) or others, like the bullfrog 

 mass, mean the frog remained in one position. Toads crawl about and 

 string the file along. Spadefoots lay a band from the base of a plant 

 to its end and then go to another plant. Most species which lay sub- 

 merged masses have the whole complement in the one mass. 



