THE ANURA OF ITHACA, N. Y. : A KEY TO 

 THEIR EGGS. 



ALBERT HAZEN WRIGHT. 



For the last four years the writer has been studying the life- 

 histories of the Anura of Ithaca, N. Y., but it will be some time 

 Taefore the work reaches completion. It seems best, however, to 

 present the following brief summary of one phase of the work, 

 in the hope that it may be of help to the numerous workers who 

 employ Anuran eggs either for comparative or experimental em- 

 bryologic purposes. 



Eight species of Anura are found at Ithaca, N. Y., namely: 

 Rana sylvatica, Hyla pickeringii, Rana pipiens, Biifo lentigmosus 

 americanus, Rana palustris, Hyla versicolor, Rana clamitans and 

 Rana catesbeiana. 



The first five species appear from hibernation and spawn under 

 a maximum air temperature of 43°-50° F. ; the last three delay 

 until the maximum reaches 70° F. or more. The first five usually 

 breed from the last of March until the middle of June ; the last 

 three, from the last of May into August. All but two species, 

 Biifo I. americanus and Rana clamitans, occupy four or five weeks 

 for the spawning period. The exceptions may require two or 

 three months. The number of eggs in a complement varies from 

 800 in Hyla pickeringii to 20,000 in Rana catesbeiana. 



The eggs of three species, Hyla versicolor, Rana clamitans and 

 Rana catesbeiana, float more or less at the surface of the water ; 

 the eggs of the other five are submerged. The five species with 

 submerged eggs are first to breed. They deposit eggs with firm 

 jelly envelopes, several eggs appearing at an emission except 

 in Hyla pickeringii, where only one appears at an emission. The 

 three with buoyant eggs breed after May 25. They deposit at 

 the surface masses or films of eggs with loose jelly envelopes^ 

 several eggs being deposited at an emission. 



At the outset the attempt to secure friutful mating with captive 

 specimens was abandoned. The effort was rather to obtain pairs 



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