30 
Psyche 
[March 
The low, broad humps on the dorsum of the dentes may be 
as many as three in number or they may be absent, and the 
short ventral seta is often reduced, or (rarely) absent. 
The apical tooth of the mucro and the apical filaments of 
the empodial appendages are often broken off so as to give a 
truncate appearance to these structures. The very small 
internal tooth on the first pair of claws may be absent in 
some specimens. 
Relationships 
The general appearance and structure of the furcula of 
this species gives it a superficial resemblance to the brevi- 
dens group (Stach, 1947) of the genus Proisotoma; how- 
ever, the reticulate integument, ventrally directed anus show 
that it is in reality allied to the tribe Anurophorini. Of the 
genera in this group it would appear to be most closely re- 
lated to Isotomodes (Axelson, 1907), Cryptpygos (Willem, 
1902), and Subisotoma (Stach, 1947). The body form and 
segmental ratios appear to be closest to Subisotoma, but the 
reticulate integument and presence of anal spines serve to 
separate it from all three genera. 
Measurements 
The pattern for measuring used in this paper requires 
some explanation. The only absolute measurements given 
are those of the holotype. All other measurements are given 
in the form of ratios. These ratios are taken for each tag- 
matal group as a comparison of all parts involved to one 
part, which is considered as a standard number, i.e., 10. 
Then the average deviation of each of the non-standard 
ratio numbers is calculated. It is hoped that this will make 
for easier comparison, as well as give some idea of the varia- 
tion involved. In all cases, the ratios were taken from those 
specimens within the given size range, and, because of the 
heterogonic growth of these animals, can only be applied to 
specimens of similar size. All individual segmental measure- 
ments are those only of the imbricate or setaceous area, 
eliminating the highly variable intersegmental membranes. 
The total size measurements, however, included these parts. 
Holotype measurement (in mm.). Total length (excl. 
