16 



General Account of the Ithacan Anura. 



Table showing the data resulting from the egg study of the eight species of Anura 

 under consideration. 



The spherical eggs are closely surrounded by a vitelline membrane 

 and one or two envelopes. In three species (the peeper, the swamp 

 cricket-frog, and the bullfrog), only one jelly envelope is present; in the 

 other six, there are two envelopes. Two forms, the pickerel-frog and the 

 tree-toad, have the lower poles yellow or yellowish. In the others they 

 are white or light cream. The black pigment of a wood-frog's egg often 

 leaves only a small white spot on the lower pole, as in the European 

 Rana temporaria. 



Four species (the peeper, the swamp cricket-frog, the tree-toad, and 

 the toad) have the vitelli from 0.9 to 1.4 mm. in diameter; the inter- 

 mediate group (the green-frog and the bullfrog) have the vitelli 1.2 

 to 1.7 mm. ; and the third group of three (the meadow-frog, the pickerel- 

 frog, and the wood-frog) have the vitelli 1.6 to 2.4 mm.; the smallest 

 of the five Ranas, the wood-frog, has the largest viteUi. 



The eggs of three species {Hyla versicolor, Rana clamata, and Rana 

 catesheiana) float more or less upon the surface and have the jelly con- 

 sistency very loose ; these three with buoyant eggs usuall}^ breed after 

 INIay 25. The eggs of the six remaining species are submerged and have 



