96 Mr. A.S. Packard on the Development 
the Hemiptera are numerous aquatic species, as there are in all 
the other suborders except the Hymenoptera, of which only two 
genera are found swimming, in the adult state, on the surface of 
pools; and they are the low minute Proctotrupids, Prestwichia 
natans and Polynema natans, Lubbock. As we have previously 
shown, the Hymenoptera do not imitate or mimic the forms of 
other insects, but, on the contrary, their forms are extensively 
copied, in the Lepidoptera and Diptera especially. There are 
synthetic types or mimetic forms which bind these suborders 
into a single series. As the Coleoptera, Hemiptera, Orthoptera, 
and Neuroptera are bound together by homomorphous or mi- 
metic forms into a series by themselves, so the Hymenoptera, 
Lepidoptera, and Diptera possess their synthetic types linking 
them together. 
Another and very accurate method of determining the relative 
rank of the larger groups in nature is by comparing the degra- 
dational forms occurring in each group. Among the Neuroptera 
the lowest wingless forms, such as Lepisma and allies, most 
strikingly resemble the Myriapods in the great equality in size 
of the arthromeres composing the body, and the slight dis- 
tinctions preserved between the three regions into which the 
body is divided. The largest, most vegetative, monstrous, and 
bizarre forms of insects are found among the Neuroptera and 
Orthoptera. Among Hemiptera the parasitic wingless lice, and 
among Coleoptera the low Meloé and Stylopide, afford instances 
of a genuine complete parasitism such as obtains more fully 
among the low Crustacea and worms. While we find the de- 
eraded types of Inseets belonging to the lower series of sub- 
orders present elongated, worm-like, myriapodous forms, in ascend- 
ing to the second and higher series of suborders, the lowest wing- 
less dipterous Pulex assumes a much compacter, more cephalized 
form ; while in the wingless Chionea, which wonderfully mimics 
the higher Arachnids, there is a still greater concentration of 
the arthromeres. This concentration of the body progresses 
towards a higher type in the degradational forms of the Lepido- 
ptera, such as the wingless females of Orgyia, Anisopteryx, and 
Hybernia. In ascending to the wingless Hymenoptera, such as 
Pezomachus, Formica, and Mutilla, there is a closer approxima- 
tion to. the winged normal form of the suborder. While in the 
lower Insects the loss of wings involves apparently a total change 
in the form of the body, in the Hymenoptera this change is re- 
markably less than in any other insects, and the tripartite form 
of the insectean body is more strongly adhered to. 
Again, in the degradational winged forms of the Hymenoptera 
we find the antenne rarely pectinated—a common occurrence im 
the lower suborders; also the wings of the minute Proctotru- 
