138 Charles K. Smith 



York populations. Geographic differences in initiation of breeding are 

 likely due to differences in temporal occurrence of weather conditions 

 that stimulate adult migration to the ponds. The later hatching time for 

 northern populations corresponds with a later breeding season. 



During 1981 my study ponds filled slowly, and water levels fluctu- 

 ated greatly during the breeding and incubation periods. Ponds 2 and 3 

 did not dry until late summer, and pond drying was not a source of 

 embryo mortality. Pond 1, however, dried completely by 22 March, des- 

 troying all egg masses. Although pond 1 partially refilled before April, 

 no additional egg masses were found. 



Egg mass data are presented in Table 2. The mean number of eggs 

 per mass (23.4) is similar to that reported by Brandon (1961) for popu- 

 lations in southern Ohio (x = 22), but greater than that reported for New 

 York populations by Bishop (1941; x = 16), Smith (1911; x = 14), and 

 Uzzell (1967; x = 14). Further study of geographic variation in the 

 number of eggs per mass is required in order to determine if this appar- 

 ent north-to-south cline is real. 



Table 2. Selected data, egg masses oi Amby stoma jeffersonianum in a central 

 Kentucky pond (pond 3). R = range, N = sample size. 





X 



1 SD 



R 



N 



Number of 









eggs per mass 



23.4 



13.5 



2-67 



105 



Length of 











single mass (mm) 



43.1 



11.9 



30-70 



26 



Diameter of 











single mass (mm) 



39.0 



8.6 



20-60 



26 



Length of masses 











in series (mm) 



117.0 



40.4 



40-200 



13 



Number of 











masses in series 



3.4 



1.0 



2-5 



13 



Depth to top 











of mass (cm) 



14.3 



3.3 



7-24 



64 



Total water depth 











at mass (cm) 



25.3 



3.0 



20-30 



64 



