The elements of insect anatomy; The elements of insect anatomy; an outline for the use of students in the entomological laboratories of Cornell University and Leland Stanford Junior University elementsofinsect00comsto Year: 1895 — 76- Note.—The student should have a clear idea of the significance of the terms generalized and specialized, which are now much used in biology. Generalized indicates a primitive condition, a nearness to ancestral forms. Thus the most generalized member of a group (as a family or an order) is that member which most clearly resembles the ancient progenitor of that gr
The elements of insect anatomy; The elements of insect anatomy; an outline for the use of students in the entomological laboratories of Cornell University and Leland Stanford Junior University elementsofinsect00comsto Year: 1895 — 76- Note.—The student should have a clear idea of the significance of the terms generalized and specialized, which are now much used in biology. Generalized indicates a primitive condition, a nearness to ancestral forms. Thus the most generalized member of a group (as a family or an order) is that member which most clearly resembles the ancient progenitor of that group. Specialized, on the other hand, indicates remoteness from the primitive t} pe, an adaptation to more special conditions of existence. Thus the most specialized member 'of a group is the one that departs most widely from the ancient pro- genitor of that group. These terms are used in a comparative sense ; thus, a highly special- ized form may be regarded as generalized when compared with forms that are still more highly specialized. A TYPICAL WING. The flies of the genus Rhyphus afford good examples of comparatively generalized wings. By studying the accom- panying figure (Fig. 2) of one of these, the student can Fig. 2.—Wing of Rhyphus. gain a good idea of the type of the wings of insects belong- ing to the order Dipt era, and have a standard with which to compare wings of insects of other orders. Longitudinal veins and cross-veins.—The veins can be grouped under two heads : first, longitudinal veins, those that normally extend proximo-distad ; and second, cross- veins, those that normally extend more or less nearly cephalo-caudad. In Figure 2, three of the cross-veins are
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