2 Region Studied and Methods Pursued. 



THE REGION STUDIED AND THE METHODS PURSUED. 



The region of this study is at the southern end of Cayuga Lake and 

 most of our observations were made in the immediate vicinity of Ithaca, 

 Xew York. In fact, it was found that on the University property 

 alone all the eight local species occurred in sufficient numbers to make 

 possible the study of their life-histories. Numerous trips beyond these 

 confines were made, but the above area proved the center of the most 

 careful attention. 



Within a radius of 3 miles of the Cornell University Campus most 

 varied localities and environments are found. The region is an area 

 of considerable glaciation and presents many different types of land 

 topography associated with such physiographic history. The city of 

 Ithaca and the Renwick marshes between the city and the southern 

 end of the lake represent a fine delta, to whose level numerous hanging 

 valleys suddenly drop. When Cayuga Lake, a former river-bed, was 

 deeply eroded, the preglacial tributary streams in the last mile or mile 

 and a half of their courses had to cut new postglacial channels to the 

 new level of the present Cayuga Lake and dropped 400 feet to accom- 

 plish this end. Two of these postglacial gorges, Cascadilla and Fall 

 Creek ravines, serve roughly as the northern and southern boundaries 

 of our campus and of the region of my immediate interest in this 

 paper. 



The northern part of the delta (Renwick marshes) was very rich in 

 Anura and harbored the whole eight species, the forms occurring in the 

 following order of abundance: meadow-frog, toad, green-frog, peeper, 

 tree-toad, pickerel-frog, bullfrog, and wood-frog. In ravines proper, 

 the pickerel-frog is the most plentiful. When the postglacial ravines 

 crossed old preglacial buried courses, amphitheaters were of ten formed 

 and in such places (Beebe Lake) dams were constructed. Hither the 

 toads, bullfrogs, green-frogs, meadow-frogs, and pickerel-frogs resort. 

 Along these water-courses, where they approach their upland, gentle- 

 sloping, preglacial course, numerous isolated pools occur near the streams. 

 To these pools (some in woods and others in the open) the green-frogs, 

 wood-frogs, peepers, and tree-toads come for breeding. In the upland 

 back-waters and widened mill-ponds near the sources of our streams, 

 the pickerel-frogs appear much in evidence. In one of our highland 

 pools seven species breed and the tree-toads are common. 



Maps of the various places were made and on each map was entered 

 every egg-cluster found on the daily visits. Each cluster was followed 

 through hatching and in some cases farther. The purpose of this method 

 was to arrive at the hatching periods. With daily visits to these ponds 

 from March 25 to August 15, the transformations could be recorded, and 

 the periods of larval life determined. 



