i8 
Annals of the Transvaal Museum 
Province from east to west is exhibited in more simple fashion by the 
water frogs: the species found at Grahamstown is Rana angolensis, the 
same as occurs throughout the Transvaal, Natal, and Rhodesia: quite a 
different species occurs at Capetown, viz. Rana fuscigula, which is 
characteristic of the western half of Cape Province. 
Again, just as each group of species has its own particular area of 
distribution, so also each individual species seems to have a special part 
of each large area for its sole occupation. So far as is known, two diurnal 
species of Solpuga never occur together, except in the case of species 
which are very distantly related. This fact may perhaps be held to 
witness against the mutation hypothesis of species formation so far as 
this group is concerned. 
Amongst the numerous more primitive species of Solpuga, only a 
few natural groups can be recognised with certainty. The northern 
section of black-striped forms includes sericea of Mashonaland, Zoutpans- 
berg district, andN. Rhodesia, celeripes of Salisbury, striata of Damaraland 
and zebrina of the Taru desert in British E. Africa. The well-marked 
section comprising cervina, collinita, and alcicornis, belongs to the 
western half of the subcontinent, being known from Clanwilliam, 
Namaqualand, Willowmore, Keetmanshoop and Kuruman. An equally 
distinct group is that of strepsiceros, spiralicornis, and serraticornis which 
occurs in S. Rhodesia, Zoutpansberg and Barberton districts; but, a near 
relative of serraticornis is the species 5. schlechteri , found in Bushmanland 
and Great Namaqualand: other species apparently referable to this 
section range far into tropical Africa, one of them keyserlingi (perhaps a 
synonym of schweinfurthi) being known to me from N. Nigeria. The 
group including schonlandi , ferox, globicornis , and sagittaria, which is 
doubtfully natural, seems to range almost over the same area as that 
occupied by the hostilis-derbiana group but it has relationships with 
central African species, for S. niassa seems to be an ally of schonlandi. 
The species Venator, lethalis, lethalis rectus, d,ndfurcifera, are undoubtedly 
closely related and belong essentially to the western portion of the sub- 
continent, Venator extending into the karroid region of the Cape. The 
precise relationships of the other species, and the inter-relationships of 
the above groups, are too uncertain to justify any general conclusions 
therefrom. 
The main facts concerning the distribution of the more familiar 
genera are given by Kraepelin in Das Tierreich. Since the publication 
of that work, the following new genera have been described from S. Africa 
by Dr Purcell: Melanoblossia, Lipophaga, Toreus, and Chelypus. So far 
as we know, they are all restricted to Southern Africa, as also is the 
genus Hexisopus : further, all five genera belong essentially to the western 
region, which includes also the Karroo and Kalahari. At present, not a 
single species of any of these genera is known to occur in Natal, Transvaal, 
Free State, or in east Cape Colony 
Hemiblossia has been recorded by Pocock from Guatemala, but other- 
wise is only known from S. Africa: this distribution points to great 
antiquity for the genus, and is in accordance with its primitive nature. 
