1894.] The Classification of the Arthropoda. 227 
HEXAPODA (-++-CHILOpPoD). DIPLopop. 
Appendage I Antenna Antenna 
se Il Mandible asd Mandible j Head 
hs Ill Maxilla 1 Lower Lip 
+ IV Maxilla 2 Foot 1 
ny Vv Thoracic Foot 1 Absent 
ss VI Thoracic Foot 2 | Foot 2 
"os NU Thoracic Foot 3 Foot 3 
“VIII Abdominal Foot 1 Absent 
_ IX Abdominal Foot 2 Absent 
Crass I—CHILOPODA. 
Insecta with elongate depressed body, no differentiation be- 
tween thorax and abdomen, all the somites being provided 
with appendages, those of the thorax-abdomen being locomo- 
tor in function. 
Crass II —HEXAPODA. 
Insecta with body consisting of not over 19 somites, divided 
into head, three-jointed thorax and abdomen. Thorax pro- 
vided with three pairs of locomotor appendages, and usually 
with two pairsof wings; abdominal appendages usually lack- 
ing from most somites, those of the extremity being usually 
modified for reproduction and sensory purposes, those of the 
other somites, when present, being weak. 
SusB-PuyLUM III—DIPLOPODA SIVE CHILOGNATHA. 
Elongate, homonomously segmented Arthropods ; head dis- 
tinct, bearing three pairs of appendages; no distinction be- 
tween thorax and abdomen; this region with numerous 
somites, all, except the anterior, having two pairs of append- 
ages (double somites), sternum narrow. Stigmata two to each 
somite, tracheæ tufted and unbranched, not anastomosing- 
Gonads single, beneath the alimentary canal; spermatoza 
quiescent; genital ducts opening between the bases of the 
second and third pairs of feet. 
