FROGS. 25 



attacliment being some 4 or 5 inches below the surface of the water. 

 This attachment serves as the apex of an inverted cone, and the 

 base of the cone spreads out on the surface of the water. This 

 also may be due to a rise in the level of the water. Rarely a mass 

 more than a foot square is recorded. Some of these masses may 

 be composite. In a certain pond, where numerous frogs had laid, 

 two bunches had been placed so close together as to make a film 

 15 by 10 inches. In another case a mass just as large was secured, 

 and the evidences of its double nature were even more evident 

 than in the preceding instance. 



For several years small isolated packets of eggs were found on 

 the water's sm'face, distributed in tne manner of tree toads' eggs, 

 but without their individual characteristics. They could not have 

 been those of the swamp cricket frogs' eggs, for this species lays 

 very early in the spring. At last it was discovered that, as egg 

 development went on, the egg masses of the green frog often lost 

 their circular disklike form, assumed irregular shapes, and sepa- 

 rated into small masses of 25 or more eggs, a natural process due 

 to the jelly becoming loose as hatching approached. But the egg 

 packets observed were composed of fresh eggs. In those instances 

 the wind or strong currents, or both, caused them to float away 

 from the original mass. 



The buUfrog begins egg la37ing at air temperatm*es of 71 to 72°, 

 or at water temperatures of 66 to 71°. On the average, however, 

 breeding comes at an air temperatm^e of 80° and at a water tem- 

 perature of 70 to 71°. The bullfrog lays the last of June or in July. 

 The author's breeding record for this ^rog extends from June 16 to 

 July 10. Doubtless it begins earlier some years or extends beyond 

 July 10 in belated seasons. The writer has taken females with ripe 

 ova the last of July. Ovulation usuaUy occurs at night, at which 

 time the species is most active. The bullfrog is a solitary form, 

 yet at the height of breeding a mill pond (PL VI, fig 2) may have a 

 dozen or more pairs in it, and some lakes may be well enough sup- 

 plied with them to furnish the famed bullfrog choruses of June 

 and July. 



UsuaUy the egg masses of the bullfrog are found among brush or 

 under similar cover (PI. XVI, fig. 1). The disk form so prevalent 

 in the egg masses of the green frog obtains with this species as well. 

 In one instance the egg mass covered a space of 2 by 2^ feet, or 5 

 square feet; in a second case, 2 by 2 feet; and in a third, 2 by 1^ 

 feet. The size of these masses is a sufficient criterion for identifica- 

 tion, since it is very miusual to find an egg mass of the green frog 

 which covers a square foot. The first of these three egg filTns was 

 deposited upon a mass of driftwood and brush, which was at the 

 sm-face; the second was found among some fresh white branches 

 that extended into the water from the edge of the pond. In rare 

 cases the masses become stringHke, due to shifting water levels. 

 One such mass was found attached to the roots of an overtm-ned 

 stump in shallow water and another in brush beneath a boathouse 

 float. Sometimes bullfrogs lay their films in midpond around 

 stumps, or attach the smiace egg film to the tips of^ overhanging 

 bushes wliich extend into the water (PI. XIII, fig. 1). The winds 

 often break these films into pieces and distribute them along the 

 shores of the lake or pond. The mass is glutinous and is not firm 



