CH. Ill] THE WINGS 39 



the wing-venation was begun by Comstock and Needham [48] and 

 continued by Needham [102], whose work stimulated further work 

 along similar lines [176, 180]. De Selys contented himself with 

 giving names to the various veins. Comstock and Needham not 

 only adopted a new terminology, in which the names of corre- 

 sponding veins and tracheae were the same, but they also intro- 

 duced the system of notation, whereby each main vein, each branch, 

 and all the more important cross-veins and wing-spaces, were also 

 designated by an abbreviation of one or more letters. This system 

 forms the basis of the notation adopted in this book. Only in a 

 few important particulars, where recent investigation has shewn 

 the earlier work to have been either incomplete or at fault, has it 

 been necessary to make alterations. The table on pp. 40-43 gives 

 the names of the principal parts of the wing, together with the 

 Selysian names, the Comstock-Needham notation, and the revised 

 notation. Veins, points, and angles are denoted by capitals; 

 spaces and areas by small letters. Foreign abbreviations, such 

 as q for cross-vein (German, quemder), have been rejected. 



In addition to the above, secondary branchings of the veins 

 may be denoted by the addition of the suffix "a" for the upper 

 or distal branch, "6" for the lower or proximal branch, of the vein 

 affected; e.g. in Aeschna, Rs bifurcates into Rs a above and Rs b 

 below, at the fork. Also, intercalated supplements running to the 

 posterior border, between branches of main veins, may be desig- 

 nated by adding the suffixes A, B, c ... in order, from the apex 

 backwards, to the vein above the supplements ; e.g. in Agrioninae 

 the "postnodal sector" is M 1A (not M la ). 



In Plate II we have figured either the whole or the more 

 important parts of wings selected as typical of the five families 

 of Odonata. The Revised Notation is printed in red on the Plate. 

 A study of this plate, in conjunction with fig. 17 (which shews the 

 trachea tion in the corresponding larval wings), will, we trust, not 

 only explain the venational scheme satisfactorily, but also justify 

 some important alterations from the familiar Comstock-Needham 

 notation. In order to study the various subfamilies in detail, 

 a series of forty-seven illustrations of typical wings is also provided, 

 to be used in conjunction with Plate II and with the venational 

 definitions given in chap. xiv. 



