23S NEW YORK STATE MUSEUM 



Opposed to this interpretation or favoring any other. It seems 

 clear that vein M^ occupies the more advantageous position; the 

 hinder branches He in the field in which reduction proceeds fastest, 

 and the stages of their disappearance are easily traced, as has been 

 illustrated for the Tipulidae in the foregoing pages. Undoubtedly, 

 in this family at least, M^ is the most persistent of the branches of 

 media. On page 155 he says, '' If the fourth vein [M] is three 

 branched and the discal cell [cell ist M^] present, the vein 

 separating the discal from the second basal [cell M] is of course 

 the first section of the proximal [posterior] branch of the fourth 

 vein [M3] ; if the fifth vein [Cu] is really the one that is three 

 branched, then this vein, at the outer end of the second 

 basal [cell M], is always a true cross vein, which it always is 

 in the Comstock system zuhen the discal cell is absent.'' The part 

 of this statement italicized above is a complete and incomprehensible 

 misstatement. Vein M^ in the Comstock system is always IVP, 

 never anything else, whether the cell ist M2 be closed or open. 

 Moreover, cell 1st M^ is merely the space in the basal part of the 

 first fork of the median vein, whether it be delimited externally 

 by a median cross vein or not. It does not depart for other 

 fields when specializations occur about it, but stays in that 

 fork. This is the difference between the Comstock system and 

 the others — it has a morphological basis. It recognizes a difference 

 between principal veins and branches of the same. It does not 

 begin in the middle of the wing to enumerate veins after a few have 

 been dismissed under a different sort of designation. It does not 

 take as its standard of comparison the most specialized of wings 

 with reduced venation. It deals primarily with the real structural 

 entities of the wings, the veins and cross veins, and not with the 

 spaces that these leave vacant. 



And the "great cross vein " of Osten Sacken (the basal deflection 

 of Cu^) will not be greatly helped by calling it some other kind of 

 a cross vein, since it is not a cross vein at all. But neither the 

 Loewian code of medieval terminology, nor the Schinerian version 

 of it — neither as corrupted by Osten Sacken nor as purified by 

 Williston — with its peregrinating posterior cells, its discal cell 

 emitting veins to the hind margin, its cross veins great and small 

 and miisconceived, and its wearisome confusion of the simplest 

 elements of the venation, needs that it should be criticized. What 

 these are and whence they came and why they work as they do are 

 self-evident. It were better to say of tfiem that they have served 

 their day and generation. 



