1916.] EF. H. Gravety: Indo-Australian Thelyphonidae. 79 
Tetrabalius seticauda (Doleschall). 
Moluccas: Halmaheira; Amboina; Ternate; Batjan; Ceram. 
Tetrabalius nasutus, Thorell. 
Borneo. 
Only one specimen is known. It is said to be a female, but 
both antenniform legs are damaged. 
It will be seen from the foregoing pages that among the Thely- 
phonidae evolution has chiefly affected three organs—the tibial 
apophyses of the male, the tarsi of the antenniform legs of the 
female, and the genital sternum of both sexes. 
The modification of the tarsi of the antenniform legs of the 
female occurs at about the place at which the male holds them 
between his chelicerae during courtship (see Gravely, 1915), 
p. 52-2, pl. xxiv, fig. 25) and there can be little doubt that it 
implies a specialization connected with this process. Species in 
which these tarsi are modified must therefore be regarded as higher 
in the evolutionary scale than allied species in which they are 
unmodified. 
Nothing definite is known as to the uses of the modified tibial 
apophyses of males; but since this modification is also confined to 
one sex it is presumably also connected in some way with sexual 
processes. In any case, since the tibial apophyses of both sexes 
of some genera, and of females of all, are alike simply conical, 
those species must clearly be regarded as most highly specialized 
in the males of which these apophyses are most widely removed 
from this fundamental form. 
With regard to the genital sterna, those species in which these 
plates undergo the greatest change when maturity is reached must 
similarly be regarded as the most highly specialized. 
Specialization of the genital sterna appears to be roughly 
correlated with specialization in other parts. Thus in the keelless 
genera, in which the antenniform legs are never modified, it is not 
known to occur in the genus Labochirus, very few members of 
which have the tibial apophysis as highly modified as is usual in 
the genus Hypoctonus ; and in the genus Hyfoctonus it appears to 
be confined to the most specialized species—z.e. to those in which 
the tibial apophyses of the male bear a distinct lamina on the 
lower border of the grooved surface. Similarly in the keeled 
group it appears to be least marked, among Indo-Australian 
forms, in the genus Uvoproctus, in which the tibial apophyses of 
the male are scarcely, and the antenniform legs of the female 
not at all, modified. Specialization of the genital sternum ap- 
pears, moreover, often to be more marked in males than in females 
in genera in which the antenniform legs of the latter are more 
strongly modified than the tibial apophyses of the former, and 
vice versa. It seems impossible to say more at present with refer- 
ence to modifications of the genital sternum. 
