AMPHIBIANS—GOIN 439 
stage into little frogs. In the gray treefrog, Hyla versicolor, for ex- 
ample, the adults go to the ponds from April to early summer to 
breed. The eggs are laid, scattered in small masses or packets of not 
more than 20 to 40 eggs each, on the surface of quiet pools. These 
packets are loosely attached to the vegetation. The egg itself is but 
slightly larger than a millimeter in diameter while the outer envelopes 
may be more than 4 mm. in diameter. The eggs hatch in 4 to 5 days 
and the tadpoles emerge to swim around and feed in the pond for 
about a month and a half to 2 months until they transform, usually in 
the middle or late summer, into small frogs that may be from 15 to 20 
mm. in snout-to-vent length. 
Ranidae.—The typical life-history pattern of the so-called “true 
frogs” of the genus ana is too well known to deserve more than pass- 
ing mention. In Rana pipiens, the leopard frog, the eggs are laid in 
the spring months. They are deposited in large masses attached to 
submerged plants, twigs, or sticks, or they may even rest on the bot- 
tom, unattached, in open ponds and marshes. After hatching, the 
tadpole exists as a sunfish-type tadpole with a very high tail fin for 
2 or 3 months. The tadpole itself is quite large and often exceeds 3 
inches in length. 
A couple of Oriental species of Rana lay their eggs out of water 
on leaves or stones or even in the mud near the bank, but these egg 
masses are essentially unmodified and the larvae which escape from 
them soon make their way into the water. This habit of laying its 
eggs out of water is also found in the South African genus PAryno- 
batrachus. All the species of Stawrois, a genus characteristic of 
mountain-torrent regions of southeastern Asia, lay their eggs in the 
pools below the cascades. These eggs hatch out into aquatic tadpoles 
that are especially adapted for life in mountain torrents by having 
large suctorial disks back of the mouth. 
In the genus Cornufer of the East Indies we find the extreme 
modification in ranid development in that, instead of hatching out 
into tadpoles which later metamorphose, development is carried on 
in the eggs which are laid on land and which hatch out directly into 
fully formed tiny froglets. 
Rhacophoridae.—The Old World tree frogs typically lay their eggs 
in masses of foam on the leaves of plants or other structures above 
the water. The habits of Rhacophorus leucomystax may be taken as 
an example. The breeding season is apparently very long, egg foam 
having been collected from late April through August. The breeding 
places include the walls of unused manure pools and sometimes the 
crops in flooded fields. If no suitable pool or other water is available, 
the egg foam may be laid on the ground during rainy evenings. 
During the process of egg laying, the female does most of the work 
