50 
PACIFIC SCIENCE, Vol. XVII, January 1963 
Reproduction 
Spawning apparently commences in January 
throughout the range of mirabilis, but the 
length of the season is uncertain. In southern 
California spawning takes place throughout the 
period from January to July ( Weisel, 1947: 
82). My observations indicate that spawning 
also starts in January in the Alviso ponds; fe- 
males hatched there in January and February, 
however, are mature and full of ripe eggs in 
August and September of the same year. It is 
Fig. 1. Chart of the study region; latitude N, longitude W. 
