Page:Phylogeny of cynipid genera and biological characteristics.pdf/2

 of the more specialized gall-wasps. Information as to the evolution of some of these phenomena is highly desirable and nothing of the biological characters of such specialized creatures can be adequately learned except as it is studied in connection with the morphological characters, careful taxonomic work, and observations of the living insects.

The data here assembled is the result of a study of the Cynipidae of the world, actual specimens of almost ninety per cent of which have been examined. Much information has been gained by a study of living material. The conclusions reached, as yet only incompletely applied to the genera of the family, will serve as the basis for a thorough revision of the classification of the Cynipidae which I hope to be able to publish soon.

I am under great obligation to the same friends who have aided my other studies of the gall-wasps: Dr. Wm. M. Wheeler, Prof. C. T. Brues, and Prof. Irving W. Bailey of the Bussey Institution of Harvard University; Nathan Banks of the Museum of Comparative Zoology; Charles W. Johnson of the Boston Society of Natural History; and Dr. Frank E. Lutz of The American Museum of Natural History.

DATA CONCERNING EVOLUTION

The wing venation of the Cynipidæ is remarkably uniform throughout the whole range of species. Only the genus Eschatocerus, with one known species, shows any considerable modification from the type; in that species the first and second cubital cells are closed by the extreme reduction of the second abscissa of the radius and of the second crossvein. The related Figitidæ show a wide range of variation from the complete cynipoid venation to a condition almost as specialized as that found in those Chalcididæ which have retained only a single vein. In the Cynipidæ the modifications are very slight, and these, e. g., the presence or absence of the areolet, the extent of the cubital vein in particular, the extent and continuity of other veins, and the angles of the veins, are characters mainly of specific or even individual worth, sometimes differing on the two sides of the same specimen.

Nevertheless, it is possible to perceive two lines of modification of the venation which seem to indicate something of group relationships: (1) the radial cell, varying from a completely closed to a wide open condition, find (2) the first abscissa of the radius, varying from an arcuate to an angulate condition.