1864.] 
448 
On Dimorphism in the Hymenopterons genus CYNIPS; with an Appendix, 
containing hints for a new Classification of Cynipidae and a list of Cynipidae, 
including descriptions of several new species, inhabiting the Oak-galls of 
Illinois. 
BY BENJ. D. WALSH, M. A. 
More than two years ago Baron Osten Sacken directed the attention 
of American Entomologists to the remarkable fact, that Hartig had 
“ collected about 28,000 galls of Gynips divisa and reared 9 to 10 
thousand Cynips ivom them, all 9 9 ’’i Gynips folil like¬ 
wise he had thousands of specimens of the 9 sex without a single % 
whence he concluded “ that these insects were agamous, or in other 
words that the % S did not exist at all.’’— {Proc. Ent. Soc. Phil. I, p. 
■ 49 .) 
I have myself examined in all, at various times, some in the closet 
and some in the field, about a thousand specimens bred from or taken 
out of the gall of Gynips querciis aciculata —a species described by 
Osten Sacken from two specimens furnished by myself—and they were 
all beyond a doubt 9 9 • There can be no mistake here, because in 
this genus the % is distinguishable at a glance by its differently shaped 
and very much smaller abdomen ; but to prevent the possibility of 
error, in most cases I ascertained the presence of the ovipositor. 
In the spring of 1863 I determined, if possible, to solve this mys¬ 
tery; and as the subject is of high physiological importance, it will be 
advisable, before stating the conclusions arrived at, to specify in some 
considerable detail, as extracted from my journal, the facts upon which 
those conclusions are based. 
The trees from which I obtained the galls, or “oak-apples” as they 
are commonly called, on which I experimented, were an isolated and 
scattering group of 50 or 60 black oaks (quercus tinctoria), situated 
on a blue-grass prairie and without any other kind of forest-trees inter¬ 
mixed with them. The distance from this group to the nearest timber- 
land is about 150 yards. For many years I have procured from this 
source just as many Gynips q. acicidata as I wanted, the galls occurring 
in prodigious exuberance there; and I had noticed three years ago that 
upon 6 or 7 of the largest black oaks in this group, on which the Gynips 
had hitherto been almost exclusively found, being cut down for fuel, 
