South African Lacertilia, Opliidia, and Batrachia. 175 
The records for this species have not been inserted; as it has 
been received from all parts of South Africa except the Kalahari 
Desert. 
This is the most widely distributed and most aquatic of the South 
African batrachians. It ordinarily lives in stagnant pools, in wells and 
vleis where no other frog is to be seen. According to Dr. Eattray it can 
tolerate brackish water and often breeds therein. When handled it 
becomes covered with a very ill-smelling foamy lather which emanates 
from the pores of the skin whilst liquid is also exuded from the vent and 
spreads over the body. This, or some other secretion, seems to be very 
poisonous : a Bana fiiscigula which happened to be placed in the same 
bottle with a Xcnopus was found to be quite dead fifteen minutes after- 
wards, though the Xenopus seemed unaffected, whilst both were covered 
with a glutinous white foam which also lined the sides of the bottle. Its 
occurrence in numerous isolated ponds seems explicable only on the sup- 
position that this species habitually migrates ; most observers agree that 
such is the case, but we have never actually witnessed a migration, which, 
however, may be usually a nocturnal function. Mr. Gunning, of Kimberley, 
informs us that one fine evening some years ago he saw a large procession 
of this species, comprising some thousands of individuals, on the march 
towards a river away from a dam which was just commencing to dry up. 
The dams frequented by Xenopus may completely dry up in winter, and 
examination of the site has revealed no buried toads and no hibernating 
individuals except for one or two juveniles which were hidden under 
stones or in other damp places. Nevertheless these toads often spend the 
winter in the liquid mud of shallow ponds, and must occasionally run the 
risk of becoming entombed under baked mud. That they may sometimes 
be thus entombed without fatal results is indicated by some facts related 
to us by Mr. Stoney, of Alexandersfontein. The duckpond at Alexanders- 
fontein was cleared out in July, 1910, when the toads were probably in a 
torpid condition, and the mud was spread over the adjacent lawns and 
grounds forming an extensive layer varying in thickness from an inch to a 
foot. A month later, when the first spring rains appeared, Xenopus Icevis 
arose in great numbers from the mud and trekked in all directions, 
invading the houses and blocking up the irrigation pipes, many of them 
perishing in the heat of the sun. It is interesting to note that they 
wandered aimlessly in various directions, in spite of the fact that the 
newly filled duckpond was only twenty or thirty yards away. In damp 
mud this toad can live for a long time without food : a few young 
specimens which were kept in a biscuit tin along with some lumps of mud 
remained there in good condition for eight months. 
The colour is normally almost black with or without irregular small 
spots, but the intensity of the colour varies much according to external 
