Annals of the Transvaal Museum 
i7 
according to their structure, it is of interest to see how those groups are 
distributed in nature. It is important however to guarantee the accuracy 
of the scheme as an index to genetic affinity, and for this reason the data 
presented by the more specialised class of diurnal species can be more 
safely used than that of the primitive nocturnal species. 
A large natural group of nine species, including hostilis, marshalli and 
derbiana , ranges over Southern Rhodesia, Transvaal, Bechuanaland 
Protectorate, Free State, Natal and Eastern Cape Colony: it does not 
occur in Western Cape Colony, the western limit, at present known, 
being at Somerset East. A small group somewhat related to this, but 
distinctly separated therefrom in structure, includes only the Capetown 
species S. vincta, the Little Namaqualand species S. spectralis, and an- 
other western form S. maraisi found at Worcester and Stellenbosch. 
Another small group, also related to the two just mentioned, includes 
erythronota of unknown locality, erythronotoides from Victoria West, and 
lateralis from the districts of Uitenhage, Port Elizabeth, and Bathurst. 
A fourth group of diurnal species, ranking as a well-marked section, 
includes the two species chelicornis and villosa, which range throughout 
the karroid regions of the Cape into Little Namaqualand. 
In addition, there are two other groups of diurnal species, neither of 
which is directly related to those already mentioned. One of them in- 
cludes hastata and two other species which are all from Great Namaqua- 
land, and no member of the group is known to occur elsewhere. Lastly, 
the very distinct section comprised by lineata and its ally brevipalpis, 
occurs widely distributed in the western and central districts of the Cape, 
excluding the Cape Peninsula: eastwards, its limit appears to be Alice- 
dale. All these diurnal groups seem to be peculiarly S. African, having, 
so far as we know, no representatives north of the Zambesi. 
It will be seen therefore that the subcontinent is thus divided up into 
so many distinct regions, each of which is the home of one particular 
natural group and that for the most part these regions do not overlap. 
An exception to this generalisation is presented in the case of the lineata 
group, which occupies almost the same region as chelicornis. The rule, 
however, only applies to groups which are sufficiently closely related: 
lineata is so remote in structure from chelicornis as almost to warrant 
generic separation therefrom. 
It is interesting to notice that these geographical regions coincide — 
but not rigidly so — with the regions occupied by the natural groups of 
other animals, belonging even to different phyla of the animal kingdom. 
The eastern area, occupied by hostilis and its immediate allies, is the 
same as that occupied by the glabrifrons-latimanus group of the scorpion 
genus Opisthophthalmus : the nearest allies of this group are: austerus, 
a Karroo species which agrees fairly with S. chelicornis and villosa in its 
range: macer , a western species which occurs near Capetown extending 
northwards as far as Worcester and Ceres, and eastwards for some dis- 
tance along the Cape Coast : crassimanus which occurs in Little Namaqua- 
land and Carnarvon, and nitidiceps its close ally which occurs in the 
Albany, Uitenhage, Somerset East and Cradock districts. The almost 
universal change of fauna experienced in passing through the Cape 
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