PSYCHE 
VOL. XLII MARCH 1935 No. 1 
PRELIMINARY NOTE ON THE STRUCTURE OF THE 
PRETARSUS AND ITS POSSIBLE PHYLOGENETIC 
SIGNIFICANCE 
By Richard T. Holway 
Biological Laboratories, Harvard University 
The uncertain reliability of morphological structures for 
determining ancestral relations is well known and the ex- 
treme care and attention to the vagaries of parallelism, spe- 
cialization, etc. so necessary for the development of valid 
theories have been rightly emphasized of recent years. How- 
ever, in spite of its late disrepute, there is yet much to be 
learned from comparative morphology if sufficiently long 
series are studied and checked with the trends of parallel 
structures and if a most judicious interpretation of the evi- 
dence is demanded. 
The primary purpose of this paper is to indicate the type 
of claw-segment found in the important insectan orders 
together with the common basic plan occurring throughout 
and also to outline possible homologies which further study 
and examination of selected and thoroughly representative 
series from each order may support. Although it is impos- 
sible at the present stage to offer any evidence substantial 
enough to warrant forming exact conclusions as to homolo- 
gies from order to order, to say nothing of attempting to 
solve phylogenetic problems, there are without doubt most 
significant agreements in many cases which provide definite 
possibilities to be tested by further study. Especially im- 
portant are those correlations which fall in with phylogen- 
etic concepts already accepted (or debated) from the evi- 
dence of the comparative morphology of other structures. 
