THE SUPPOSED NYMPHS OF THE 
PALPEODICTYOPTERA 1 
By F. M. Carpenter 
Harvard University 
Our knowledge of the metamorphosis of Carbonifer- 
ous insects is meager. Inferences have been made 
about their immature stages, but actual knowledge is 
restricted to the fossils which have been found. Fur- 
thermore, although some Carboniferous nymphs are 
known, it is difficult to associate them with adults. Spe- 
cific association is obviously impossible; the best that 
can be done is association by family or order. If the 
fossils concerned are members of an existing order, the 
association can be made with near certainty, for the 
living immature and imaginal forms provide a basis for 
comparison; but if the fossils are adults belonging to 
an extinct order, the problem of identifying their imma- 
ture stages is more difficult. This is well illustrated by 
the nymphs which have been referred to the extinct order 
Palaeodictyoptera, and which have been extensively dis- 
cussed in the literature on wing development. Specu- 
lation about these nymphs and their significance has been 
so great that I have thought it worth-while to summarize 
here what is actually known about them. 
Five palaeodictyopterous nymphs have been described 
up to the present time, four by Handlirsch (1906) and 
one by Goldenberg (1873). All are from Carboniferous 
strata. Through the courtesy of Dr. R. S. Bassler and 
Dr. Gf. A. Cooper, I have been able to examine the four 
Handlirsch specimens in the United States National Mu- 
seum. I have not seen the Goldenberg fossil, which is 
in the collection of the Natural History Society at Bonn, 
Germany, but it has been redescribed and figured by v. 
Schlechtendal (1913J and Guthorl (1934). Handlirsch 
placed all these species in tPs “form genus” Palceodic- 
tyopteron, but he also used that term as a generic name 
1 Published wfth a grant from the Museum of Comparative Zoology 
at Harvard College. 
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