798 MR EDWARD J. BLES ON THE 
during the twilight until he seizes the female. There is nothing resembling the 
courtship of Urodeles. The male makes a sudden dash and clasps his mate round 
the lumbar region; his arms are too short to meet on the ventral surface. In the — 
amplexus being inguinal, Xenopus resembles the Discoglosside and Pelobatidee 
(BouLencrr, '97, p. 69). The note of the male changes at the commencement of 
pairing. In a low tone he utters ‘cd, cé6, cd, c6, ....” and at each syllable 
strikes the under side of his head against the back of the female. Between each 
stroke the floor of the mouth of the male is seen to bulge considerably so as to 
carry his head away from the back of the female. When spawning begins he is 
silent, but every now and again while the amplexus lasts he croaks loudly during 
the short intervals when oviposition stops. 
The account given by Lestiz (’90) of the breeding of Xenopus speaks only of 
spawning taking place in August, z.e. the South African spring. 
According to my observations, I should conclude that, like Discoglossids, the 
same female may spawn in the wild state several times during the sprmg and summer, 
and that the males are ready to pair at any time in those seasons. My female Xenopus 
had spawned for the first time in the year in February (Cambridge), April (Cambridge), 
and May (Glasgow), in successive years, for a second time in June, and a third time at 
the end of August in the same summer (Glasgow, 1902); in the following year three 
batches of eggs were laid at corresponding times. Thus the animals became acclima- 
tised to a difference of six months in the seasonal changes. 
Hach batch of mature eggs was usually deposited in the course of five days, one 
night in which pairing did not take place intervening between the nights when eggs 
were laid. On one occasion spawning took place on five nights; between the third and 
fourth night of spawning there was an interval of three nights; the others were on 
alternate nights as usual. 
It has so often happened that male and female have been seen to cast their skin 
the morning after pairing, that it is probable that ecdysis is usual at this time. The 
skin is loosened all over the body, the legs are then freed, and the skin which is 
attached to the snout is drawn forward, crammed into the mouth, and eaten in exactly 
the same way as it is by many terrestrial frogs. 
Oviposition.—The amplexus is continued from the evening until the next morning, 
and may last until 9 a.m. Spawning does not commence immediately, but may begin 
an hour after pairing. From this time onwards eggs are laid at frequent intervals all 
through the night. As a rule the eggs are laid singly, and the pair swim about or 
come to the surface to breathe between each act of spawning, But occasionally three 
or four eggs are laid in quick succession in the same spot, and somewhat rarely eight 
to ten eggs will be emitted in a group. 
The egg is held between the three protruding flap-like lips of the cloacal spout, 
while the pair swim about restlessly for half a minute to two minutes; the female then 
grasps a long leaf or a twig of water-plant between her outstretched feet, and the pair 
