638 THE PAXOEPOID COMPLEX, ii., 



micrutrichia. Thus we may (H^•ide the Order into two groups, 

 as follows: — 



(1 ). 'J'he more archaic families, with microtrichia still present. 

 These are the Ithoiildw, IIe7)u>rohiidie, Dilaridct, Sisyridcf, Conio- 

 pteiyyidfc, Fsychojjsidct!, Folystcechetidce^ and Osmylidce. 



(2). The more specialised families, witli microtrichia absent. 

 These are the TrichomatklfP,, Bei'othkln', Chrysopidce, Apochrysidf^', 

 Mantisjjidff, Nynqjhidce^ Xemopieridie^ Mynnelpontidce, and Asca- 

 laphidw. 



r-^ -_» '^ 



'rL-xi-ii-.-i;:;. 



Portion of a main vein and sunoundint; membrane from the win*; of Mirro- 

 nms tasinrunrr Walk., to .show the triehiation: ( x 200). 



Ill the first group, macrotrichia are never found upon the true 

 cioss \eins. In the second, we find in the Trirhvmatidw and 

 Bci-dfli'uhv forms showing the passage of the macrutrichia from 

 the main veins on to the cross-veins. For instance, in the geiuis 

 Stt'iiohlplla, the cross veins remain without macrotrichia, as in the 

 first group. In SpermophorHla, (jne or two isolated macrotrichia 

 may be found upon most of the cross-veins. In Trichoma, there 

 is an intense proliferation of mao'otrichia upon the main veins; 

 and they overflow, not only on to the cross-veins, but also, in 

 some places, even on to the membrane itself. .Vs this genus is 

 evidently specialised in its excessive hairiness, there can be little 

 doubt that this latter occurrence is in the nature of a ca:'nogenetic 

 development, and is not to be cjnsidered as an archaic survival 

 of macrotrichia from an original archedictyon. 



