28 CLAUDE FULLER. 



111. THE XO.\JENCL.VJ'URE AND NUMBERING OF 

 THE WING-RIBS. 



The two systems of naming' and numbering now proposed 

 rest upon evidence which will be given in a subsequent section. 

 In introducing them here sequence has been subordinated to 

 other considerations, it being impossible to proceed without 

 a recognisable nomenclature. The notation is secondary to 

 the nomenclatnre, and is suggested to meet the frequency 

 with which certain principal tracheas, and, therefore, certain 

 principal ribs are duplicated. Upon the whole both systems 

 indicate that there is no fundamental difference between the 

 venation of the termite wing and the wings of other general- 

 ised insects. 



0. Costa. — The costa of common acceptance. The term 

 is employed to describe that part of the ambient which is 

 moditied into a chitinised and stiff rib for the support of the 

 outer ' margin of the wing. (Exceptionally, as in the hind 

 wings of Cal o term es and Cry ptotermes, the costa nuiy 

 be composed of costa and post-costa.) 



\, la,. I'ost-costa. — This is an oljsolete term reintroduced 

 to describe the first auxiliary, a reduced principal rib. The 

 term distinguishes it frotu the second auxiliary or sub-costa. 

 The post-costal trachea is probably often homologous with 

 the sinq)ie costal trachea of Comstock and Needham, where 

 it appears —as in the case of the hind wings of Calotermes 

 and Cryptotermes — to ])recede the costa. 



II, Jla. Sub-costa. — This rib is: (1) the radius of 

 Holmgren ; (2) Desneux' ju'incipal branch (R. 1) uf the radius; 

 (o) Hagen and Sjostedt's branch of the sub-costa. 



JJl. Radius.— This is: (I) the radius uf Desneiix ; (2) 

 the radial sector of Holmgren; (o) the sub-costa of Hagen, 

 Sjostedt, and others. The ])re-existing trachea of the rib, in 

 siicli generalised forms tis ilodotermes and Calotermes, 

 very greatly resembles the condition found in the cockroach. 



' Tiie lennite wing is regarded ;is possessing only two margins, an 

 outer and an inner. 



