io8 
Annals of the Transvaal Museum 
pp. 84-87. In passing, it may be noted that Mr Tucker’s descriptions of 
the two new species of Stasimopus, based on adult males, should be supple- 
mented by comparative or absolute measurements of the palpal segments I 
and of the segments of the first leg. Such data are of primary importance. 
p. 97. Under the heading of Homostola zebrina Purcell, Mr Tucker says: 
“This species has been included by Hewitt as a synonym of Spiroctenus : 
but — “it seems fairly clear that Purcell’s zebrina is rightly referred to the genus 
Homostola, and further that it is not synonymous with Spiroctenus.” In a 
further note on p. 136, in reference to my later work on Spiroctenus ( Homostola ) 
zebrina, he adds: “I have examined Hewitt’s specimens both male and female 
and consider them to be true Homostola sp. zebrina and can hardly agree that they 
are Spiroctenidae though the two genera have much in common .” 
Now firstly, although Mr Tucker speaks with confidence regarding the 
actual identity of the genus Homostola Simon, yet there is considerable un- 
certainty on the matter: I have never seen any specimen agreeing with the 
description of the genotype H. vulpecula, nor had Dr Purcell when he described 
zebrina : certainly, Simon’s description of the generic characters “Ungues 
postici serie unica dentium 6-7 inaequalium armati” and “metatarsi antici. . . 
parce et minutissimi aculeati” does not readily admit of the inclusion of 
zebrina therein. 
As regards the relation between H. zebrina Purcell and the genus Spiro- 
ctenus, Mr Tucker’s remarks are truly ambiguous: he admits that “the genera 
have much in common,” yet alluding to actual specimens of zebrina that I 
lent him, “can hardly agree that they are Spiroctenidae.” What does this 
mean? 
The chief point at issue is the taxonomic value of the sternal sigilla. In 
Simon’s great work, the Histoire Naturelle des Araignees, this character was 
utilised in separating large groups of genera from each other, and later 
workers still seem to regard the character with favour. On the other hand, 
I am convinced that its value in classification has been greatly over-rated. 
The size and position of the posterior sigilla varies considerably during the 
lifetime of the same individual in various species of Pelmatorycter : the genera 
Pelmatorycter and Ancylotrypa as redefined by Mr Tucker, represent the oppo- 
site extremes of sigilla variation, yet are completely linked up by inter- 
mediate forms, and the relationship existing between extreme types is borne 
out by a study of the nests they construct. (See account of nests of Pelma- 
torycter crudeni and P. parvus — which latter would be called Ancylotrypa 
by Mr Tucker — in 5 . Afr. Journal of Science, 1916, July.) 
My views will be understood from the accompanying figure, which is an 
exact copy of that published in Mr Tucker’s paper and used by him to 
emphasize the essential difference between Pelmatorycter and Ancylotrypa. 
The figures A — D represent the sterna with sigilla of the males of four distinct 
species. A and C are referred by Mr Tucker to the genus Ancylotrypa: this 
well illustrates the fact that the number of sigilla does not signify, as a generic 
character. B and D are referred by Mr Tucker to the genus Pelmatorycter: 
these considered either alone, or in conjunction with A and C, show that 
position of sigilla is also of little value. There remains only to be considered 
the shape of the posterior sigilla, for it happens that both species chosen to 
represent Pelmatorycter have sigilla with pointed tails : however, his descrip- 
tion of that genus commences “ Posterior sternal sigilla large, oval or pear- 
shaped, and median to submedian in position.” As regards actual size, the 
character is too variable to be admitted as a basis for generic separation. It 
