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Indiana University Studies 
the body. Spatheg aster, on the contrary, is more slender, the wings 
larger and more elongate, always extending a bit beyond the body; the 
antennae are less than two-thirds the length of the body; and finally, 
the abdomen is less developed. The shape and size of the abdomen de- 
pend largely on the form and the size of the ovipositor. Even when the 
ovipositor is very long, as with Neiiroterus Ixviusculus, it is, while at 
rest, withdrawn into the abdomen where it is wrapped into a spiral. The 
amount of space demanded by this ovipositor necessitates a considerable 
development of the abdomen. 
All of which merely emphasizes that the differences depend 
upon the different modes of reproduction. Even such char- 
acters as the relative lengths of antennae or wings and abdo- 
men are dependent upon the development of the abdomen. 
Good taxonomic characters are not really very abundant 
between these alternate generations, and Adler admitted this. 
The characters of the ovipositor, however, are of considerable 
interest, and certainly should be studied in our American 
species. But these ovipositor characters could never have 
been sufficient grounds for maintaining two genera, and it is 
hardly warranted to state that apparent genera are alternate 
generations. 
For the corresponding generation, Spatheg aster, the ovipositor is 
entirely different. Small and delicate, it does not take up much room 
in the abdominal cavity, which results in an entirely differently formed 
abdomen. The differences in ovipositors are constant, altho in other 
respects the two generations may resemble each other considerably. 
Thus, fumipennis and tricolor are, in respect to form and color, so 
similar that they might be ccnfounded in a superficial examination. But 
if one further considers the general structure, the form of the abdomen, 
the lengths and the form of the wings, and particularly the ovipositor, 
the differences between the two generations are well marked. ***>!= 
Therefore [because of the differences in ovipositors] the contours are 
very different in the two insects. The manner in which Spatheg as teo-' 
pricks the: leaves demands great mobility in the abdomen, so we find 
it nicely petiolate; in the N ewroterus, on the contrary, it is almost ses- 
sile. Then, the Spathegaster searches for leaves of a particular sort, 
very tender, as a suitable spot for the eggs; it is therefore requisite 
that it be able to fly easily; so we find it equipped with longer and larger 
wings than the Neuroterus, which, for its part, does not particularly 
need the ability to fly, for the buds for its oviposition are never lacking. 
Since one may, so to speak, reconstruct a cynipid when one knows 
its ovipositor, it is understandable that it may furnish the definitive 
characters between diverse species. When two correspondent genera- 
tions have different modes of living, it is desirable, above all things, that 
the ovipositor be modified and be of the form suitable for oviposition. 
* * * * * The ovipositor of Neuroterus has a bent tip and cannot 
