FROGS. 27 



or two lines or fibs within one jelly tube. The eggs of the spade- 

 foot usually hatch in a very short period. 



While the hermit spadefoot lays eggs in bands like the European 

 forms of this family, the spadefoots of the Southwest — namely, 

 Couch's and Hammond's spadefoots — may strew them on the 

 bottom of the ponds. These eggs may be singly placed or be in 

 more or less agglutinated masses usually one egg deep and may be 

 laid as late as mid-August. This peculiar arrangement of the egg 

 complements may be due to the absence of suitable vegetation, 

 since Strecker" has seen Couch's spadefoots lay egg bands which 

 became attached to grass, etc. 



The life histories of several smaller true frogs are unknown. These, 

 including Cope's frog, the yellow-legged frog, and Rana onca, are 

 too small to be considered. 



The wood frog usually chooses still water for spawning, rarely 

 backwaters or bayous of streams. It prefers the leaf-laden ponds 

 (PL VIII, fig. 1) and transient pools of wooded districts, though 

 not wholly restricted to such localities. Occasionally the author 

 has seen the frogs migrating to swampy cat-tail stretches for spawn- 

 ing and has both observed and heard them in such situations. Two 

 of his best collecting spots were a grassy pool and a high upland 

 pond, both of which were out in the open and ordinarily dried up 

 in midsummer. In wooded districts he has found them even using 

 pools no more than H by 4 feet in area. When the air temperatures 

 average 53 to 58°, one may go out with some expectation of finding 

 the wood frogs spawning, provided the water temperature is at 

 least 41 to 48°. Spawning reaches its height usually at about 53 

 to 60°. The average date of spawning is about April 4; the author's 

 earliest record is March 19; his latest first record, April 14. In 

 general, wood frogs spawn most frequently in the fii'st half of April, 

 though occasionally earlier or later, depending on the season. In 

 some years, when spring opens early, as the last of March, the spawn- 

 ing begins with a rush, and the species may be practically through 

 laying within from four to six days after the beginning of ovulation. 

 Most of the egg complements are laid at night, yet the author has 

 frequent instances in which the eggs were laid during the day, both 

 in the laboratory and in the field. In the laboratory, they have 

 been observed to lay throughout the day; in the field, there have 

 been numerous indications that eggs were laid during the day. 

 This species is gregarious at the breeding season. Where the first 

 bunch of eggs of the season is laid, one is quite certain to find other 

 wood frogs depositing their complements later. In this way the 

 whole egg content of a large pond may frequently be massed in a 

 small Umited area (PI. XVIII, fig. 3). 



The eggs of the wood frog may be deposited either near the edges 

 or in the middle of the pond. They are usually attached to grass 

 stems, weed stalks, twigs, or brush; but, in rare cases, they may 

 rest free on the bottom. In this species the egg bunches tend to be 

 attached more frequently than in the case of the leopard frog. In 

 rare cases, wood-frog and leopard-frog masses are found on the 

 same twig. The egg mass, at the time of laying, may be an inch in 

 diameter. Within one-half hour to two hours it assumes a diameter 



« Strecker, J. L.: Notes on the life history of Scaphiopus couchii Baird. Proceedings, Biological Society 

 of Washington, Vol. XXI, p. 203. Washington, 1908. 



