4 
Psyche 
[March - June 
tions from the norm in several of these curves. The most striking is in 
connection with one population of P. hirsuta which has a longer 
fourth abdominal segment than is normal, and in all of the specimens 
examined of P. duodecim punctata which have the manubrium, longer 
than is normal in the remaining species. It is quite probable that more 
exhaustive analysis will point out more such exceptions; however, it is 
apparent that there is little difference among the various species in 
most organ ratios. 
The genus Pseudosine/la under any definition is a patently polyphy- 
letic group with characteristics largely determined by a particular 
ecology ; it can be distinguished from its ancestral genus Lepidocyrtus 
upon only one basis — the reduction in the number of eyes. Pseudosi- 
nella usually shows additional characteristics in the loss of pigment 
and the modification of the unguis structure, either through great 
elongation and reduction in the size and number of inner teeth and/or 
through the enlargement of the basal inner ungual teeth. Within the 
North American cave forms there are three and possibly four separate 
evolutionary lines involved. Only one of these, the group including 
Graph 2. Curves for five different organ ratios, each curve being a com- 
posite of all species. In the key below the ordinate is given first in each case. 
A: cephalic diagonal/second theoracic segment; B: cephalic diagonal/third 
tibiotarsus; C: manubrium/mucrodens ; D: cephalic diagonal/mucrodens ; 
E: cephalic diagonal/fourth abdominal segment. 
