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 



