Annals of the Transvaal Museum 
hi 
Mr Tucker’s proposal to establish a new genus, Segregara, on those 
ij Acanthodons (excluding Gorgyrella) which have three pairs of sigilla, only 
adds to the difficulties of systematists, and is open to the still more serious 
objection that it conveys an impression of discontinuity which actually does 
not exist. I am quite satisfied that in a natural system of classification the 
species which “ are distinct in the possession of 3 pairs of small marginal 
sigilla” should not be generically separated from those otherwise similar 
species which have only two such pairs. Acanthodon microps usually has two 
pairs of sigilla, but occasionally has three pairs. The very first species 
mentioned by Mr Tucker as referable to his genus Idiops, as thus restricted, 
will witness against the advantage of basing genera on meristic variations — 
the trisigillate form is primitive — of this kind, for I have a specimen of 
spiricola which on one side presents three sigilla, but on the other side only two. 
It is admitted however that the position of sigilla relative to the margin 
of the sternum is of rather more importance, and thus the genus Gorgyrella 
has better claims for recognition. Still, a study of the Transvaal species has 
convinced me of the impossibility of separating genera on this character. 
There seems to me no justification for generically separating Acanthodon 
transvaalensis from schreineri as proposed by Mr Tucker. My conclusions are 
also supported by habitudinal characters. There is a small Transvaal form of 
Gorgyrella which I can only recognize as a variety {minor) of schreineri 1 : 
only recently have I learnt, from _ Mr G. van Dam, that this spider has a 
remarkable type of lid, closely resembling that of abrahami 2 (the type of 
Segregara). We know that considerable differences are found amongst the 
lids of the different members of a genus, but it seems most improbable that 
species which agree together in making a lid so characteristic as that of 
abrahami can belong to different genera. 
Lastly, Mr Tucker’s speculations on the generic migrations and origins of 
the Idiopeae are by no means convincing. He says : “ Now Pocock, writing on 
the geographical distribution of the Ctenizidae {P.Z.S. 1903) considers that 
Idiops reached South America, not from N. America but from Africa. This 
and the general geographical distribution of the Idiopeae indicate that Tropical 
Africa was the seat of origin of the group.” And again : “ Finally, Gorgyrella can 
also be regarded as an off-shoot from form (A) and it is important in that it 
lends support to the theory of the South African origin of the Idiopeae in that 
it is found in S. Africa alone.” This interpretation of the great diversity of 
form that obtains in Southern Africa may happen to be actually correct, but 
is certainly not adequately supported by facts. The Idiopine fauna in most 
parts of its extensive range through the warmer parts of the world has scarcely 
been touched, and we know absolutely nothing whatever of its geological 
history. To-day, Africa is the headquarters of Antelopes, yet H. F. Osborn 
tells us “it is probable that the Antelopes together with the entire stock of 
Cavicornia, including the Bovinae, or cattle, originated in Asia.” (See his 
Age of Mammals.) 
The apparent absence of Idiopine genera from the south-west parts of the 
Cape, and from Madagascar, will probably be more generally interpreted as 
signifying the comparatively recent arrival of this group in Africa. 
Any attempt to correlate the evolution of the group as a whole with the 
known facts of distribution must be of very doubtful value, so long as the 
available data are so very imperfect. 
1 See G. van Dam and A. Roberts in Annals Transvaal Mus. vol. v, p. 223. 
2 See F. Cruden in S. Afr. Journal of Science, July 1916. 
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