.^1) I III: lll.MX MWIU.I. <)l< (<)l.l'/>ri I'.KA .IKKNI'.V 11 



the Hubmcnturn arifl the <,i:rv'd.( or'in. A ]><>'it.'i\>\e llnr of *)<••/< l',(,fri<iil ;o»y 

 have been the chitinization of the (j-rVAorin ari'l the <\\VA,\i\>fMfHt\n;<ii \hr 

 sutureH s<;7)arat,in(; it, from the [>0!4tj(eTiae. 'I he broa/l area hflw*-^n the 

 occipital foramen anH Ihc submcritum woul'l in «uch a 'aw be a rnoiUftcHr- 

 tion of part, or all of the cervau»ria. It i« much easier t/; belierve, ir)»t,e*'), 

 that because of the mernbranoua fx»ri'litior) of the c^rva/y^ria, no str'/rijj 

 resistance was offered to an ai>proac h of the rneRal rr)ar(;ins of the chitin'/u* 

 fKjstgenae, which wouM rnitjrate thus* to nerve asi a firm f'/un'lati'/nal 

 support for the submentum, as well as to ^trengfheTi the v/li^lity '/f the 

 head-capsule, as a whole. The mesal marj^ins would in time apprf/»ch 

 so clf>se as to press the two sides of the c/jrva^z/ria into a line. Fu*ion '>f th« 

 mesal margins of the f>'<stj;enae would finally take pla/.,e,and the c,«rvac/»fia 

 would be divided intf< two part-., rjrie jTart would be att,a^,he/J t/> th« *uV>- 

 mentum entirely separated from that \><>r\.UAi 'A the c,«rva</>ria \t<iT'\i^\rt% 

 the occipital foramen, and would be finally rttiw^td U> a suture. 'f^K 

 other part of the ccrvacoria would remain as a p'/rti'/n f>f the c«tv>x. 

 Whether the mesal marj^ins of the postjjenae would appr'/a^b the mev/n 

 as broad surfaces, or as narrow ones and later clonj^at^, it would l>< dif- 

 ficult to state with certainty, th'>usf,h the latter would probably happen. 

 In the primitive cole'>pterous hea/1 it is rv^t unlikely that the hea/1 was 

 much shorter, and that the area between the 'xxipital foramen and the 

 submentum was correspondin^rly sh''/rt,er, v^ that there w/uld n/^t be the 

 necessity for a broad fusion of the me^al mar^p'n of the p'/it^fenae. So 

 far as observed there has been retained in no c/,<le^/pterous hea/J any 

 marks of the line of fusion of the pr/ttgcnae. 



Abundant evidence is found for the c/>T)Ciusiorj that the broad area 

 between the occipital foramen and the submentum must be a part of the 

 postgenae. A similar a^»ndition as in the C^Je^ypfJiTa is pre»>rr.t in many 

 families of iasects. In many Hymen/>ptera the rr:*^.?) rra'r''' ''f the p'At' 

 genae are fused between the occipital foramer^ =; '-n of tJi* 



labium. That this Ls the true interpretation ',• svyTrn l>r 



the fact that there is often a suture on the mer-'ryr. -,.';0 *. ..-.;^ i.-e ,.,-.e of f ijaion, 

 and is further substantiated by the fact that this area. l-,iears or, it» ventral 

 margin the paracoilae. In all oclorrhaphous and orthorr^oapho'is Iriptera 

 the area ventrad of the occipital foramen Is a contir.uo'ij chitirrized piece, 

 similar to that found in the Coleoptera. ar*d is derived from th.Ji fisw-yr. of 

 the mesal margins of the p^z-tger^ae. 



It may be well to add here that the ezpr-^ 

 as applied to the changed location of such a =• - 

 may be onh- relati-vely correct in its s-ugfestior.. 

 cipital foramen in Coleoptera has m.'?.-a"'r: '.■.'■-.'. 4 

 this typical foiiticn. Sticfa a mli^z. 

 tion of the ventral scrface, with a oo.. , . . ,.. 



