76 University of California PuUications. [Entomology 



region, and the wing remains a more efficient organ for flight. 

 Also as a consequence the venation in this region does not 

 become obliterated to the extent that it does in the basal 

 region. The cross veins along the basal edge of the mem- 

 branous portion of the wing have become specialized into a 

 strong transverse vein, from which in many cases all the other 

 veins seem to arise, because of the obliteration of their basal 

 connections. 



The coordination of the wing with various parts of the body 

 is, like the last, a development to accommodate the wing when 

 at rest. Either edge may be involved, or the coordination 

 may show itself in changes on the disk of the wing. It 

 is always the front wing that is modified. The front edge 

 is sometimes made to conform to the shape of the body so that 

 it will fit closely. Generally the body is modified at the same 

 time, the adjustment being mutual. In many beetles and in a 

 few Hemiptera there is a special provision for holding the wing 

 against the body; but none of these adjustments greatly affect 

 the venation, except locally. The hind edge modifications are 

 of a similar sort, and are equally barren of great results upon 

 the venation. 



The modifications that occur on the disk of the wing consist 

 of a fold, usually quite abrupt, whereby the wing brings itself 

 into general conformity with the shape of the body. This 

 fold usually occurs just in front of the first posterior vein, and 

 when present divides the wing sharply at that point into two 

 regions. Commonly the line of fold is bordered on either side 

 by a strong vein, and is not crossed by cross veins, but only 

 by the marginal vein at the end. This fold has been usually 

 identified with a line found in many insects where no actual 

 fold occurs, and with the first folding line of the hind wings. 

 All of these lines can not be considered homologous, however, 

 as will be brought out in the discussion of the venation of the 

 different groups. Where the fold occurs in the front wing it 

 certainly influences very profoundly the adjacent venation. 



The modification of the hind wing that most nearly cor- 

 responds to this front-wing fold is the system of folds whereby 

 the wing is made to occupy as little space as possible when 

 at rest, so that it will be protected by the front wing. The 

 fold in these wings is always a full ISO degrees, so that the 

 folded wing lies flat. All Avings, except those of the Odonata 



