Mr Bles, On the breeding habits of Xenopus laevis Baud. 221 
in their food. The aquarium stood in a sunny place in the 
summer and in a dark corner of a living-room during the winter. 
During January, 1899, the females refused food and the males 
took very little; this behaviour continued until Feb. 20th when 
one female died. On dissection her ovaries were found to contain 
quantities of mature ova ready to fall into the body-cavity. The 
three survivors were taken to the University Botanic Garden 
and through the kindness of Mr Lynch, the Curator, I was allowed 
to enclose a corner of the Tropical Lily Tank, about 10 ft. by 3 ft., 
with wire netting and put the frogs there (Feb. 23rd). Spawning 
commenced on the night of Feb. 28th. 
When in the lily tank, in water at 22° — 24° C., the frogs ate 
earthworms voraciously every day. The first sign that breeding 
is about to take place is the appearance of a dark patch on each 
hand and arm of the male. The darkening is caused by closely 
set, minute pointed spines which seem to be formed of thickened 
cuticle like the nuptial asperities on the hands of some European 
frogs. The extent of the patch is along the whole of the arm 
from the axilla to the tips of the fingers and it is in such a 
position that the whole inwardly directed surface of the arm 
and the back, not the palm, of the hand becomes roughened 
where it presses against the female during the pairing. No 
other nuptial changes were seen in the male, and in the female, 
the only alteration besides the greatly distended abdomen was 
an increased vascularisation and turgidity of the short cloacal 
spout. 
The night before the eggs were laid, the male commenced 
croaking at dusk and, I believe, continued this for some hours. 
The sound produced is a continuous metallic rattle, almost exactly 
like the noise of winding a large clock with a key and with 
a similar alternating high and low note. This is distinctly audible 
ten yards off*. The female is perfectly mute, so far as I know; 
like the females of other frogs and the difference is correlated 
with the dimorphism of the anatomy of the larynx, here more 
strongly marked than in any other Anura. The only way to 
identify the individual making sounds is to remove or disturb the 
others, as there is absolutely no outward movement discernible, 
not even in the gular and pectoral region. 
The male continues croaking until within four or five minutes 
before pairing, while the female remains motionless at the surface 
of the water with her nostrils and eyes above the surface. He 
then swims quietly up behind the female and from a distance of 
about six inches makes a sudden dash at her. The amplexus is 
inguinal and lasts the whole of the time of spawning, that is from 
dusk until dawn. I followed the process of segmentation during 
one night and could therefore judge the length of time which had 
