The Green-frog, Rana damata Daudin. 73 



It would seem that when the air-maxima approach 80 the species 

 breeds commonly. During June and the first part of July the eggs of 

 this form are very common ; thereafter they diminish in numbers until 

 the last of July or the first of August, when a few stragglers deposit 

 the last eggs of the Anuran breeding season. Our latest records for 

 eggs are: July 29, 1904; July 24, 1906; August 10, 1907; July 24,1908; 

 July 22, 1909; July 25, 1911. 



Surface temperatures are probably very influential because of the 

 position of the eggs. The average of 28 breeding records gives a range 

 of coincident surface-temperatures from 65 to 88 degrees or an average 

 of 76 degrees, only two records being below 68 degrees. In conclusion, 

 we hold that when the air-maxima reach 65 to 74 degrees or the water- 

 surfaces 68 to 76 degrees, Rana damata ought to begin its breeding. 



THE EGG-LAYING PROCESS. 



This species lays almost entirely at night. Its solitary habit makes 

 it difficult to capture mated pairs in the field. Evidently, from the 

 form of the egg-mass, it keeps in one position or within a very small 

 circumscribed area. The observations on the other species of Rana 

 would lead one to expect that the female voided her whole egg-comple- 

 ment at one sitting. Furthermore, from experiences with other forms 

 which lay their whole complement in one mass, it has been noted that 

 any tendency to change of position conduced to frayed masses or sub- 

 divisions of the original mass this condition of egg-mass being rarely 

 if ever observed with a fresh green-frog mass. Recently (last of 

 June 1914) Dr. G. C. Embody saw at 10 a. m., in one of his private 

 ponds, a mated pair of green-frogs. At I h 30 m p. m., in another pond, 

 3 feet away, he saw them jumping around and one chasing the other. 

 At 3 p. m. he found the pair mated among burr-reed, water-cress, 

 Elodea, and grass, where one-half of their egg-complement was already 

 laid before discovery. The uncompleted film looked as if made up of 

 half a dozen or more component masses which later merged into one. 

 The pair were under observation for 10 minutes and during this 

 period they laid two of the packets of eggs. The packet is laid | to 

 1 inch beneath the surface of the water and rises to form a part of 

 the film. As the eggs came out, a slight wiggling or change of posi- 

 tion was noticed. 



THE EGGS. 



The mass of eggs floats on the surface of the water (Plate xvn, Fig. 3) . 

 The typical form is a disc-like film (Plate vi, Fig. 5) of a single layer of eggs, 

 loosely attached or free. They may be in the middle (Plate i, Fig. 2A) 

 of the pond, where it is filled with a cover of algae at the surface, or with 

 Nitella, Chara, Myriophyllum, Ceratophyllum, or similar water-plants, 

 which make a mat of vegetation from the bottom to the surface, or where 

 isolated patches of grass, Alisma, etc., grow in the middle of a pond. 

 Usually, without such conditions the masses are about the edges (Plate 



