Hinckley.] 86 [October 4 r 



* 



water's surface only occasionally giving a subdued croak or quack. 

 At 52° they are active and clamorous. 



When first seen in the spring, the coloring of this species As- 

 dull, owing to the condition of the outer skin, which is soon shed y 

 leaving the frogs brilliant in tint. The females, at the time of 

 egg-laying, I have found invariably lighter in color than the males. 

 Both sexes, however, as is known, are subject to variableness of 

 shade in the same individual. In making a drawing I have found 

 the change so rapid and continual as to render it difficult to se- 

 cure a correct representation of color. If the glass containing the 

 frog was placed on white paper, in a full light, the skin would 

 frequently change from the ordinary shade of brown, to light ashy 

 fawn, in the course of fifteen minutes. On moving the jar away 

 from the light to a dark surface of wood or woollen, the frog 

 would as soon return to its original color. 



The note of sylvatica peculiar to the mating season I have only 

 seen or known to be given by the males, and only when m the 

 water ; it consists of a repeated croak or quack, and may be heard 

 at any time of day or night when the temperature is favorable. 

 The mouth remains closed and each time the sound is uttered 

 the side of the body over each lung is distended into an oblong 

 sac. This clamor has often been mistaken for ducks quacking, 

 but when near enough one finds it more liquid in tone. In 

 " Early Spring in Massachusetts," p. 228, Thoreau describes the 

 note, " Wurrk wurrk wurr r k wurk." During the mating season 

 the males will give voice in confinement, under favorable condi- 

 tions of water and temperature. In addition to the notes already 

 described, I have heard the young frogs reared in captivity give a 

 single musical "chip," not unlike the call note of the song-sparrow. 

 The note was uttered at intervals, in the excitement of capturing 

 flies on which they were fed. Owing to the frog's extreme shy- 

 ness I have never been able to detect the sound in the field. 



The eggs are deposited near the shore where the frogs first 

 congregate and the temperature of the water is most favorable. 

 They are of a deep chocolate-brown color on the upper surface, 

 and whitish beneath. When first laid they are held closely to- 

 gether by a gelatinous substance, which, after a few hours in the 

 water, begins to increase in size, and gradually changes from a 

 bluish to greenish tint. These masses of eggs are attached to 



