314 



PS r CHE. 



[December 1895- 



1 would also designate the two veins 

 called by Redtenbacher VI (postmedia 

 ofComstock) and VII, simply as vein 

 VII. Cubitus as well as radius is 

 characterized by the persistence of its 

 branches. As defined by Redtenbacher 

 cubitus in the Ephemerid wing has lost 

 all of its branches. This is extreme 

 specialization. In my opinion cubitus 

 in the Ephemerid wing forks at the very 

 base producing the effect of two inde- 

 pendent longitudinal veins. The same 

 effect is shown in Nemura (see figure 

 3, especially hind wing) and is inter- 

 preted by * Redtenbacher exactly as I 

 would interpret the similar condition in 

 the Ephemeridae. Nemura, indeed, in 

 the condition of both radius and cubitus 

 is very like the Ephemerid wing and it 

 is interesting to note Redtenbacher's 

 interpretation (fig. 3) of the venation of 

 this wing. No longer constrained by 

 the rigid limits which the application 

 of the theory of original convex and 

 concave veins entailed we can now 

 hardly justify the acceptance of two 

 such variant interpretations of two such 

 essentially similar wings. 



In my view, therefore, the. veins of 

 the Ephemerid wing should be homol- 

 ogized as indicated in t figure 4. The 

 interpretation does away with any 

 recognition of veins IV (premedia) and 

 VI (postmedia) as independent veins. 



either as original principal veins (Red- 

 tenbacher) or as venae spuriae (Com- 

 stock) . 



More convincing than the argument 

 from analogy for the correctness of this 



* I recognize, of course, thai Redtenbacher's interpreta- 

 tions are influenced always by the convex and concave vein 

 theory. 



t Evidently, if this interpretation is correct and veins IV 

 and VI are not elsewhere found as original principal veins, 

 the veins should be numbered as follows : I = costa, 1 1 = 

 subcosta, III = radius, IV = media, V = cubitus. 



Fig. 4 



interpret. ition is the observed fact that 

 the tracheal trunk (original basis of the 

 vein) of the radial sector can be dis- . 

 tinctly traced, at least in observed 

 instances, as a primary branch of the 

 radial tracheal trunk, although the 



chitinous envelop of the sector's tracheal 

 • .... 



branch, which gives the vein its visi- 

 bility to the naked eye, is not present at 

 the base of the sector. In studying the 

 venation of certain Blattid wings I 

 found that the wing could be so 

 mounted that the tracheal trunks (or, 

 more accurately, probably, the *•' Rip- 

 penstrange,'" relicts of the original 

 tracheal trunks and identical in course 

 with them), the foundations of the 

 present visible veins, could frequently 

 be seen and traced. At the base of any 

 wing the thick chitin envelop of a vein 

 is often obsolete although the tracheal 

 trunk persists. In a mounted wing of 

 Hexagenia sp. I have plainly ob- 

 served the branching trachea of the 

 sector arising from the radial trunk at 



* Korschelt, E., and Heider. K. Lehrbuch der verglei- 

 chenden Entwicklungsgeschichte der wirbellosen Thiere, p, 

 864, 1890- 



