^3^ NEW YORK STATE MUSEUM 



more probable by reason of the fact that in the more generalized 

 Ptychopteridae, Macrochile.[pl. 4, fig. i], Tanyderus [pi. 4, fig. 2] 

 and Idioplasta [pi. 5 ; fig. i ] , M^ is strongly deflected toward the 

 forward basal deflection of Cu^ and strongly attached thereto; 

 and there is no reason for believing that this union, so important 

 and constant a feature of the cord, once attained would again 

 be lost in this series. 



This conclusion involves, however, a departure from the 

 interpretation Professor Comstock has given for the branching 

 of. the median vein in Dixa and perhaps in other nematocera. 

 Dixa is nearly enough allied to Ptychoptera so that I must hold 

 the same interpretation for it. I would label the tips of its 

 median vein as M^ and M^ and not as M^+2 and M^. But, I 

 hope some day to have opportunity for studying other nema- 

 tocera and establishing this matter by more abundant evidence. 



/ in the diagram represents the condition of the median vein 

 found in the fossil Rhabdinobrochus as figured by Scudder. It 

 is fairly typical. And taken in connection with the apparent 

 spur or rudiment of M^ shown in figure i of plate 17 has tempted 

 me to depart from the interpretation given by Professor Com- 

 stock in another more important particular, to change the 

 designation M^ in all other crane flies to M^ But a spur in a 

 single wing is altogether insufficient evidence for so sweeping 

 a change. Furthermore, there is in certain Tipulinae^ a furrow 

 traversing cell ist M^ and running outward to the margin which 

 is chitinized along its margins; and it is not impossible that 

 this chitin line may have been the extra vein figured by Scudder, 

 although that would not be characteristic of his marked keenness of 

 observation. I believe that further knowledge of crane flies, 

 both recent and fossil, will prove whether four branches of a 

 median vein are ever present, and if both M^ and M"* really 

 occur, in what order and manner they have disappeared. 



The ordinary course of reduction of Media is further shown 

 in the figure at h, i, j, k, /, none of which is hypothetical. In 

 i, vein M^ is about equally supported at its base upon its de- 

 flected base and the median cross vein, and when either support 

 disappears, naturally it is the cross vein that disappears as a 

 irule. But the exceptions are shown at m, n, and /> of the 

 diagram, in which the deflection at the base disappears, leaving 



^ It is sho^yn particularly well in an undescribed Holorusia in my collec- 

 tion from the Cameroons. 



