VIIi 



— 83 — 



I regret that this conclusion was not reached before the figures and 

 descriptions of wings in " Corns lock's Manual for the Study of I11- 

 sects " were prepared. Should 

 a second edition of this work 

 be needed, it is quite probable 

 that a revised system of num- 

 bering the wing-veins will be 

 adopted in it. The beginning 

 student, however, is advised 

 to use in this course the sys- 

 tem given on page 80, in order 

 to avoid confusion when using 

 the " Manual. " It should be 

 remembered that, although it 

 is exceedingly desirable that 

 all entomologists should use 

 the same system of number- 

 ing the wing-veins, the adop- 

 tion of any particular system 

 is of much less importance 

 than a clear knowledge of the 

 homologies of the wing-veins. 



The following table shows 

 what seems to the writer to be 

 the most simple and hence the 

 most desirable system of numbering 



Costa = vein I. 



Subcosta — vein II. 



Radius = vein III. 



Media = vein IV. 



Cubitus = vein V. 



Anal furrow = vein VI. 



Other anal veins = veins VII, VIII, et al. 



The above system agrees with that proposed by Spuler and adopted 

 by Packard, in not numbering premedia and postmedia. But it differs 

 in a very important particular from the S3'Stem of these writers. They 

 do not number costa, but begin with subcosta, which they term vein I. 



In defense of this, Dr. Packard says :* " Spuler shares the opinion 

 of Fritz Miiller (Termitidae), Brauer and Redtenbacher (Libellulidae), 

 and Haase (Papilionidas), that costa is only a hypodermal structure, a 

 thickening of the edge, which does not have a trachea as its origin 

 (anlage), and which, therefore, has nothing to do with the veins." 



It may be that the costa does not originate in the same way as other 



Fig. 6. — Wings of Clisiocampa. 

 the wing-veins : — 



*/. c, p. 236. 



