386 NOTES ON THE BREEDING HABITS 



closure of the Light Pole by the Dark Pole ; (7) Effect of Tem- 

 perature; (8) Time of Hatching, etc. ; (9) Methods of Technique. 



I. —Time of Laying, and Localities.— The observations were 

 made in the vicinity of Baltimore, Md., during the spring months 

 of the years 'S8, '89, '90, '91. I shall only speak of those species 

 of whose indentity I am certain. Other and more imperfect obser- 

 vations are left out. The first frogs to lay, and amongst the very 

 first {Acris gryllus excepted) to appear, are the wood-frogs, Rana 

 Sylvatica. A few warm days in early spring time suffice to bring 

 them out. The following records give a general idea as to the 

 time: — February 23rd, '91, and March 8th, 9th, and loth, '90. 

 The eggs of these had been laid several days. The egg bunches 

 are found in small pools on the edges of woods, generally among 

 the low hills, and are often stuck to twigs of bushes. The bunches 

 are generally large, four to six inches in diameter, and contain very 

 many good sized eggs. In the same pool it is quite usual to find 

 the firmer egg-bunches of A7nblystoma, as this Urodele also lays 

 its eggs very early. 



Somewhat later, two species of tree-frogs appear in the small 

 pools in the woods, generally in quite small, and therefore, during 

 the daytime, often quite warm, puddles ; sometimes in the same 

 pools as the wood-frogs, oftener in the ditches by the side of the 

 road. These tree-frogs are Hyla Pickeri?igii and Chorophilus 

 triseriatus. They are often found paired, and may be, in this 

 condition, carried to the laboratory, where they continue to lay for 

 hours without abatement. The eggs of these species are very 

 similar, and I know no certain method of distinguishing one from 

 the other. The bunches are small, attached to bits of grass, or lie 

 simply at the bottom, and each bunch contains from five or six to 

 fifteen or twenty eggs. I have the following record of times at 

 which the eggs were found : Hyla — March 9th, loth, 13th, April 

 5th, '90; Chorophilus — February 23rd, '91, and March 13th 

 and 24th, '90. 



The eggs of Ratia halecina are found still later, sometimes in 

 the same localities as the wood-frogs, often in pools in the open 

 ground quite away from the woods. The eggs are individually 

 smaller, so that, although the jelly masses are often as large as 

 those of the wood-frogs, the number of eggs is greater. The fol- 



