74 The Green-frog, Rana clamata Daudin. 



XVII, Fig. 3) of the pond attached to grass, smartweed, etc., either 

 growing in or extending into the water ; in 100 or more cases hardly an 

 exception has been noted to the surface deposition, but a few apparent 

 exceptions have occurred. One egg-complement was in a somewhat 

 scattered mass (1 foot in diameter) on leaves and twigs partially sub- 

 merged. In another instance some of the complement was at the sur- 

 face and the rest in water 4 to 6 inches deep. Inasmuch as such masses 

 were found some time after their deposition, a rise in level of the pond 

 could easily have made this anomalous condition. Another variation 

 in egg-mass is occasionally recorded. The mass may be attached to 

 grass stems, the point of attachment being some 4 or 5 inches below 

 the surface of the water. This attachment serves as the apex of an 

 inverted cone, and the base of the cone spreads out on the surface of 

 the water. This also may be due to a rise in level of water. 



The lowering of the water-levels and the drying up of ponds prove 

 the most serious dangers to eggs of this species. The eggs are laid 

 in summer, the season when such phenomena occur with frequency. 

 The short hatching period is one of the factors which saves many a 

 mass from destruction. About the edges of ponds, spoiled egg-masses 

 of this species are found every year. They are whitish in appearance 

 when in a bad condition. Sometimes they are hung up high and dry, 

 the entire mass being destroyed; at other times a portion hatches 

 before the whole complement is doomed. 



Rarely, a mass more than a foot square is recorded. Some of these 

 may be composite. On June 15, 1910, in a certain pond where numer- 

 ous pairs had laid, two bunches had been placed so close together as to 

 make one film 15 by 10 inches. In another case, a mass just as large was 

 secured, but here the evidences of its double nature were more evident. 



For several years, we found small isolated packets (Plate xvii. 

 Fig. 2) of eggs on the water's surface, distributed as tree-toad's eggs but 

 without their individual characters. They could not be those of 

 Chorophilus, for this species is not in this region. At last we found that, 

 as egg-development went on, the egg-masses of the green-frog often lost 

 their circular form, assumed irregular shapes, and separated into small 

 masses of 25 or more eggs. In this case, it was a natural process due 

 to the jelly becoming loose as hatching approached. But the egg-packets 

 w'ere of fresh eggs. In these instances, the wind or strong currents or 

 both caused them to float away from the original mass.* 



The eggs have white vegetative and black animal poles. The outer 

 envelopes range from 5.6 to 6.0 mm. in diameter, 5.7 mm. being the 

 average, 6.0 mm. the mode. The middle envelope may be other than 

 spherical and often has an elliptical form; it varies from 2.8 to 4.0 mm. 

 in diameter; the average is 3.3 mm., the mode 3.0 mm. The vitellus 

 ranges from 1.2 to 1.7 mm., the average 1.4 mm., the mode 1.2 mm. 

 (Text-figure Id.) 



*Recent observations explain this phenomenon nicely. The eggs are laid in separate 

 packets which later merge in one filmy mass. The same condition obtains in Rana catesbeiana. 



