THE GENERAL FEATURES OF WINGS 65 



of the base of the wing, which occurs at the change to the adult form, the 

 bases of these tracheae are crowded together, which results in the coalescing 

 of the bases of two or more veins, so that they appear as a single vein. For 

 this reason the figure of the hypothetical type (Fig. 51) is made to represent 

 the tracheation of a nymph ; and the different tracheae are designated by 

 the same terms as are the veins to which they correspond. By representing 

 the wing of a nymph, we are able to represent the basal connections of the 

 tracheae that precede the wing-veins, and thus show which are principal 

 veins and which are branches of them. 



A glance at Figure 51 will show that there are eight principal veins; 

 and that the second, third, fourth, and fifth are branched. The names of 

 these veins and the abbreviations by which they are designated are as 

 follows, beginning with the one nearest the costal margin : 



Names of veins Abbreviations 



Costa C 



Subcosta Sc 



Radius R 



Media M 



Cubitus Cu 



First Anal ist A 



Second Anal 2d A 



Third Anal 3d A 



Enderlein ('02) has revived the old name axillaris and applied it to the 

 second and third anal veins, which he designates as axi, and a.v'2 respectively, 

 and applies, the term an alls to the first anal vein. He states that he does 

 this in order to better characterize the morphologically different veins 

 grouped as anal veins (Z, c. p. 15). But he does not state in what respect 

 the second and third anal veins differ morphologically from the first anal 

 vein. I see no reason for making the change that he suggests. 



The names of the wing-veins used in the uniform teiTninology arc those 

 adopted by Redtenbacher in his work upon which this terminology was 

 based. The terms costa, subcosta, radius, cubitus, and anal veins were 

 selected by this author from those alread}^ in use; the term media was 

 proposed by him for what appears to be the middle vein, ''in der That als 

 die 'Mittelader' erscheint," that is as the vena media. The changing of this 

 term to the masculine fonn, "medius," as has been done by several recent 

 writers, is unwarranted. 



The chief branches of the wing-veins of the preanal area. — The chief 

 branches of the principal veins are numbered, beginning with the branch 

 nearest to the costal margin of the wing. The term used to designate a 

 branch of a vein is fonned by compounding the name of the vein with a 

 numeral indicating the number of the branch. The names of the branches 



