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mainly on the entomology of the Biological Station field, one 
each on the Odonata, the Ephemerida, the fresh-water Mollusca, 
and the aquatic Coleoptera.’ The order of procedure which I 
have endeavored to pursue in the preparation of these papers, 
and which seems to lead to the most satisfactory and accurate 
results, is as follows: First, the collection of a large quantity of 
material and data under the greatest possible variety of con- 
ditions as to locality, surroundings, stage of water, season and 
time of day; then the careful study of these, in connection with 
the literature, and the making of copious notes and sketches 
preliminary to the preparation of manuscript, all evident 
deficiencies either in material or data being carefully noted 
down; next, a return to the field at the times and places indi- 
cated by the previous collections for the special purpose of 
supplying, as far as possible, these deficiencies, and finally, 
after further study of the literature, the writing of the manu- 
seript. 
In the preparation of the paper on the Odonata I have had 
the valued assistance of Prof. J. G. Needham and Mr. C. C. 
Adams, who have furnished the systematic work on the nymphs 
and Hanis respectively, while it has been my part to discuss 
the biology and ecology of the group and of its species and to 
combine the several manuscripts into a single paper— now 
nearly ready for the press. Under Mr. Adams’s supervision the 
State Laboratory Artist, Miss Hart, has prepared a valuable 
series of 134 drawings illustrating the abdominal structures of 
nearly all our Illinois species, and a series of general drawings 
of the nymphs and their distinguishing structures is well 
under way. 
For the article on the Ephemerida, the Station collections 
and notes have all been examined and the results are nearly 
ready to be put into manuscript form. It would add greatly to 
the usefulness of the paper, however, if a study of the large 
series of nymphs of this order in the seerhl collections of the 
State Laboratory could be made before the article is completed. 
Much time and labor have been spent on the Mollusca in the 
endeavor to place the study of this group on a truly scientific 
basis. Not merely the shell, but all parts of the animal were 
studied, full use being made of the unusual facilities at the 
