102 CALIFORNIA ACADEMY OF SCIENCES. [3D See, 



the mass. These stria? converging toward the hilum are 

 shown in fig. 12. 



The average number of eggs at a laying seems to be 

 about sixty for each female, these being distributed in three 

 or four of the masses. This I conclude from actual count, 

 in several instances, of eggs deposited in the laboratory, and 

 also from numerous cases where about this number and 

 distribution have been observed in streams and ponds so 

 isolated from all others as to make it probable that they were 

 all produced at a laying and by one female. 



A single laying extends over about two days, gener- 

 ally. Whether the same individual has more than one 

 period of egg-laying during a season I do not know, but 

 strongly suspect that in some instances, at least, such is the 

 case. 



The eggs are, like those of other amphibians, perfectly 

 spherical, and are considerably more highly pigmented on 

 the animal hemisphere than on the other. There is, how- 

 ever, much less pigment present than is the rule with the 

 eggs of this group of animals. In some instances I have 

 noticed but little difference between the two hemispheres as 

 regards pigmentation. 



The eggs are about 2.5 mm. in diameter. 



They can be extracted from the gelatin with comparative 

 ease, so that in this regard they are favorable for stud}^. 



Eggs kept in the laboratory hatch, i. e., the larvae escape 

 from the gelatin, in about thirty days from the time of their 

 deposition. 



Undoubtedly, as with many other animals, the rate of 

 development of the embryo is subject to considerable varia- 

 tion, depending upon the varying temperature of the water 

 in which they are contained. But I have made no observa 

 tions on this point. 



