NO. 1438. WINGS OF rifE TEXrifREDINOTDEA—MAcrjJLLIVRAY. 601 



about twice as far as in ['(Oinirn.s ; in the Ljdidie, Meg'alodontitUe, 

 and most Tenthredinida> it arises a considerable distance beyond tlie 

 origin of the sector; while in Treiiiex{^g. !»1), ^>/7/.s%sv/.s- (tig. ^T)^ Lycaota 

 (tig. 55), Acidophoiui^ and the subfamily Blennocampina? (tig. 72), it 

 arises at or just before the middle of the cell Ki+., but the moditi- 

 cation found in these genera is undoubtedly due to the atrophy of the 

 free part of K^. 



As soon as M separates from the radial sector it extends trans- 

 versely until it joins the medio-cubital cross-vein, where it usually 

 l)ends at about a right angle and extends longitudinally. About mid- 

 way between its union with the medio-cubital cross-vein and the margin 

 of the wing it divides into two branches, Mj, which extends direct to 

 the wing margin, occupying a position very similar to the same vein 

 in the front w^ing, and M.,, which extends transversely to near the mid- 

 dle of its length where it joins the medial cross-vein, from which 

 point it extends longitudinally to the margin of the wing. 



The medial cross-vein extends longitudinally toward the base of the 

 wing, where it joins a vein which extends longitudinally or obliquely 

 fiom the cubital end of the medio-cubital cross-vein. That portion of 

 this vein which lies between the medio-cubital cross-vein and the 

 medial cross-vein is the free parts of M^ and Cu^, the free part of 

 M^+Cuj being wanting, while that portion which lies t)etween the 

 medial cross- vein and the tip of the anal veins is the free part of Mg. 

 In the front wings there is a branch which extends from the stem of 

 M and joins M., just before its union with the medial cross- vein. This 

 is the stem of M^+i and is entirely wanting in the hind wings of all 

 Hymenoptera. If the position of Mj, M^, Mg, and the medial cross- 

 vein be compared with the corresponding veins in the front wings it 

 will be seen that they occupy a similar position and are in fact the 

 most important landmarks in homologizing the veins of the hind wings. 



In Oryssus (tig. 97), Blennocampa (tig. 72), Aoidophora., Perreyia^ 

 Lohoceras (tig. S2), Acordulecera (tig. 83), Pterygopherus (tig. Si), and 

 Perga (lig. 84), the transverse part of M., has atrophied so that the 

 cells Mj and 1st M.^ are united. 



The free part of M., in most Tenthredinoidea extends almost trans- 

 versly to the margin of the wing, but in the Cephidas (tigs. 93-96), 

 Tenthredinina? (tigs. 56-58), and Manoxyela (tig. 34), where the anal 

 area of the wing has been greatl}' reduced longitudinall}-, the free 

 part of M3 has been bent abruptly toward the base of the wing. 

 While in most genera the free parts of M3 and M^ are subequal in 

 length, yet in Lohoceras (fig. 82) and Perga (tig. 84), M^ is two or three 

 times as long as M3, while in the CephidiB (tigs. 93-96), Tremex (tig. 

 91), and Pterygophorus (fig. 81) M3 is several times the length of M^. 

 The medial cross-vein is in most genera subequal in length with the 

 longitudinal part of M.^, yet in AVr/.v (fig. 89), Tremex {^g. 91), Serico- 



