434 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1959 
year from early spring to late fall, males emerge from their burrows 
and move to temporary rain-filled pools where they call vigorously. 
Calling takes place both by day and by night. When the females 
reach the ponds, they are clasped by the males and egg deposition 
occurs. The toads cling to a stiff spear of grass or other piece of 
vegetation beneath the surface of the water and slowly crawl up the 
stem, in a few minutes depositing a string of about 200 eggs. The 
tiny eggs hatch in a fairly short period of time, depending in part on 
water temperature and other external factors which have yet to be 
determined. Under certain conditions they may hatch within a day 
and ahalf. The little tadpoles remain in the pool for a varied period 
of time, depending again on conditions within the drying-up pool. 
That local environmental conditions have their effect can be easily 
demonstrated. My wife and I have taken tadpoles from a drying 
pool in our backyard and put them on the back porch in a jar of water 
from the pool, leaving other tadpoles in the puddle. Those tads left 
in the puddle emerged just prior to the drying up of the pond, while 
those in the jar of water on the back porch continued to exist for 
several weeks afterward as untransformed tadpoles. 
On the other hand, in the Old World pelobatid Sooglossus seychel- 
lensis the eggs are laid on land and the tadpoles are carried about 
adhering to the male’s back where they undergo their development. 
The eggs are fairly large and the larvae hatch with hind-leg rudiments 
present, but have neither external nor internal gills at any stage of 
development. 
Pipidae.—Three types of life history are exemplified by the very 
aquatic frogs of the family Pipidae. In the Old World forms, such 
as the African clawed frog, Xenopus, the eggs are deposited in the 
water and are attached to weeds. On the other hand, in the five 
American species, including the Surmam toad, Pipa pipa, eggs are 
placed in pouches on the backs of the females. These pouches are 
temporary pits formed in the soft skin of the dorsum. Development 
is direct in two species and probably also in a third, but in the other 
two the eggs hatch into tadpoles that resemble those of the Old World 
species. 
Discoglossidae-—The mating behavior of the obstetrical toad, 
Alytes obstetricans, has been worked out in rather careful detail. The 
males call from small holes in the ground. Mating occurs on the 
ground nearby and is apt to last most of the night. The male clasps 
the female tightly around the head above the forelimbs and gently 
massages her cloacal region with his toes. Just before the eggs are 
laid, the male moves his hind legs forward so that his heels are to- 
gether anterior to and above the cloaca of the female. As the eggs are 
emitted the male catches the mass in his feet and, by stretching his 
legs backward, delivers from 20 to 60 eggs which the female expels 
