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from it are adopted, the Tracheate Arthropoda must for the future be 
divided into two sections, the first to contain the Pauropoda and 
Diplopoda and the second the Chilopoda, Symphyla and Hexopoda. 
For the former I propose the name Progoneata and for the latter 
Opisthogoneata. Furthermore if it be admitted that the affinities 
between the Symphyla and Chilopoda are greater than these between 
the Symphyla and the Hexopoda, the Symphyla and Chilopoda may be 
united as a group for which the name Homopoda is suggested. 
The characters of these divisions of the Tracheata may be briefly 
set forth as follows: 
A. The generative organs open in the anterior part of the body, appa- | 
rently on the third metacephalic somite . . . . . PROGONEATA. 
a. Antennae branched; the segments of the body in the adult are 
not formed by the fusion of two embryonic somites etc. 
Class. Pauropoda, Lubbock. 
b. Antennae simple; some of the segments of the body in the adults 
result from the fusion of two embryonic somites etc. | 
Class. Diplopoda, Blainville. 
B. The generative organs open at the posterior end of the body close | 
to,the anus PRE . +  OPISTHOGONEATA. 
a. The A region voi the Lu: ye divisible into distinct 
regions, being composed of a series of similar or approximately 
similar somites, each of which bears a single pair of ambulatory 
appendages... . siete LOTR ORDO 
a. Two (perhaps ico pairs a os feet biunguiculate etc. 
Class. Symphyla, Ryder. 
8. Four pairs of gnathites; feet tipped with one claw etc. 
Class. Chilopoda. 
b. The metacephalic region of the body divisible into two distinct | 
regions, the anterior of which, composed of three somites, bears | 
three pairs of legs, while the posterior is never in the adult fur- | 
nished with ambulatory appendages. . . . . . Hexopoda. | 
Class. Hexopoda. 
As a phylogenetic tree this classification may be represented as | 
follows: 
Diplopoda Pauropoda Chilopoda Hexopoda 
| | Symphyla | 
| pa 
Progoneata Opisthogoneata 
Pe ee Men EE 
Tracheata 
