PLECTROTAXY OF CENTIPEDES—CRABILL 407 
The striking scarcity of entire spur series in Monotarsobius, Nampabius, 
and Sigibius, upon analysis, is of considerable diagnostic utility. 
Thus, in Nampabius fungiferopes Chamberlin (table 5), only four 
series are regularly present: DTiA, VIrM, VPM, VTiM. A fifth 
series, VFM, may or may not manifest itself by a single spur on leg 
13. <A related form, Nampabius virginiensis Chamberlin (table 6), 
characteristically and in contrast lacks only DCA, DPA, VCM, VPA, 
VFP, VTiA, and VTiP; it thus exhibits series never observed in fungi- 
feropes but at the same time lacks series commonly seen in the majority 
of North American Lithobiinae. This criterion, the complete and 
consistent absence of an entire spur series, is surely the most reliable 
of plectrotaxic characters. It is either of specific or of higher cate- 
gorical significance. 
Finally, it is obviously of prime importance to determine how 
dispersion may be correlated with age. In investigating the age- 
plectrotaxy factor, N. pullus and aristeus were selected. The plectro- 
taxy of a typical praematurus and of a typical maturus is summarized 
in tables 10 and 11. The double column on the left shows the anterior 
dispersional limits of the various series for a praematurus and for a 
maturus specimen. The right-hand column presents posterior dis- 
persional data for the same two age variants. 
It is apparent that posterior dispersion in pullus is inconclusive 
but that certain spur series clearly reflect anterior variation as a 
function of age; VPP varies considerably and is perhaps the best 
indicator, but the age factor is also manifest in VTiA, DPM, and 
VFP, all on the anterior limits side of the chart. The remaining 
series appear to be unreliable. 
A somewhat similar picture is seen in aristeus (table 11). Here 
VFP, VTiA, and VPP are excellent indicators of immaturity, but 
DPM does not appear to be meaningful. Such data cannot fail to 
impress one with the dangerous possibilities inherent in designating 
a new form solely on the basis of a single specimen’s ventral quan- 
titative plectrotaxy without regard to valid non-plectrotaxic cor- 
relative criteria. Nonetheless, this very practice has plagued lithobiid 
systematics in the United States and abroad in the past, and it still 
enjoys great favor today. 
