25 
The following figure (No 3) illustrates the nomenclature here used: 
Fig - . 3. (After Buckton.) 
A , upper wing' of Siphonophora; B, the lower wing of same; a, sub-costal vein or cubitus* 
posterior margin; c, costa or costal vein; d, third discoidal or cubital vein; e first fork 
or first fureal vein; /. second fork or second furcal vein; y, second discoidal vein; h, first 
discoidal \ ein, i, the base or points of insertion; h, apex or apical margin; /, sigmatic or 
fourth vein; p, booklet; 1, costal cell; 2, basal cell; 3, first discoidal cell; 4, second dis- 
coidal cell; o, infra-marginal cell; 6, marginal cell; 7, second cubital cell; 8, first cubital 
cell; 9, stigma. 
Note.—N os. 5 and 6 are sometimes called apical cells. 
As illustrations of some of these different forms of venation 1 pre 
sent here a few figures representing different groups: 
Fig. 4. 
APHIS MALI. 
Fig. 5. 
SCH1ZONEUR A. 
Fig. 6 
TETRANEURA. 
CHERMES. 
