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University of California Publications in Zoology [Vol. 27 
The climatic charts presented herewith (figs. A-E) indicate the 
seasonal fluctuations in temperature and moisture which are of im- 
portance to aquatic spawning amphibians, and, in some degree, to the 
land-spawning forms (Plethodontidae) as well. These charts are to 
be studied in connection with the chart showing the spawning seasons 
(fig. F). Data (from Henry, 1906) are presented for three stations, 
Ithaca,, New York, representative of the northeastern United States, 
where Wright’s (1914) observations were made; Waco, Texas, where 
Strecker’s data (1908, 1910) were obtained; and Napa, California. 
The latter station, rather than Berkeley, was selected for reference in 
the present paper because it is more typical of the average conditions 
obtaining in interior California. 
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Dec. Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. 
Fig. E. Number of days per month with 0.01 inch or more precipitation, at 
Napa, Waco, and Ithaca. See figure A for legend. 
In brief, the climate at Ithaca (figs. A-E, ), involves a 
winter cold season with low average, maximum, and minimum air 
temperatures (December to March), followed by a long period when 
even the air minima are high; the rainfall (including snowfall in 
terms of rainfall) is distributed through the year with an average 
of two inches or more throughout the summer season (April to Sep- 
tember) and with an average occurrence of precipitation on 12 days 
per month during the growth period for amphibians. The summer 
season is therefore hot and moist. 
At Waco (figs. A-E, ), the temperatures of the winter 
period are high (above 40° F.), the summer maxima, minima, and 
averages are the highest of the three stations, the maximum rainfall 
comes in the spring (March to May), and the number of days per 
month on which rain falls averages close to 4 throughout the year. 
This is a hot climate, with optimum moisture conditions for the 
spawning of amphibians in the middle spring months. 
