REPORT OF THE STATE ENTOMOLOGIST I907 



235 



many aberrancies ; and there is one here in the little group of genera 

 of more typical Eriopterini shown on plate 2T,. The upcreep of the 

 tips of the two veins under discussion toward the apex of the wing 

 has already been noted in an earlier place for its effect upon the 

 development of the cell ist M^. It is also noteworthy for having 

 relieved the deflected base of M^^., of its ordinary responsibility. 

 That deflected portion in Mesocyphona tends to atrophy, and thereby 

 to reduce the rearward extension of the cord. 



In like manner vein M^ is deflected upward just beyond its 

 union with Cu^ and thereafter it tends to atrophy as in Dicranomyia, 

 or to be reattached to vein ]\P+- in the manner already discussed, 

 and more fully illustrated in the accompanying diagram [fig. 16]. 



If any one would comprehend what has happened to the 

 median vein in the Tipulidae, let him study the wings of the 

 plates carefully in comparison with this diagram, a is the hy- 



pothetical typical media, with the dotted lines in this and in 

 all the following indicating the positions of the cross veins. 

 b, c, d and e represent the Ptychopterid line of specialization. 

 b is Macrochile, with the media reduced to three branches ; c 

 is a hypothetical form introduced to account for the disappear- 

 ance of the posterior division of the first median fork^. 



Material is lacking to fill this gap, and another interpreta- 

 tion is possible : i. e. that, starting with a form somewhat like 

 Megistocera [pi. 16, fig. 4] the median cross vein has been lost 

 and the branches have regularly and progressively fused to- 

 gether, ]\'P and M" completely, leaving these same two tips in 

 Ptychoptera to be designated as M^+2 and M^. But the first 

 interpretation is certainly admiss'ble, from the frequent tend- 

 ency of M^ and M* to atrophy; and it is rendered much the 



^ This makes two tips of media remaining in Ptychoptera M' and ikf". 



