CLASSIFICATION 7 
The naturalness of the phylum Arthropoda has been ques- 
tioned by Kingsley and Packard. The latter author recently 
divided Arthropoda into five independent phyla, holding that 
Fia. 8. 
INSECTA 
CHILOPODA 
DIPLOPODA 
CRUSTACEA 
ARACHNIDA 
MALACOPODA 
ANNELIDA 
ARTHROPODA 
Diagram to indicate the origin of Arthropoda. 
“there was no common ancestor of the Arthropoda as a 
whole, and that the group is a polyphyletic one.” ‘This icono- 
clastic view, however, by emphasizing unduly the structural 
differences among arthropods, tends to conceal the many deep- 
seated resemblances that exist between the classes of Arthro- 
poda. 
Carpenter, in a most sagacious summary of the whole sub- 
ject of arthropod relationships, has recently brought together 
no little evidence in favor of a revised form of the old Mul- 
lerian theory of crustacean origins. He traces all the classes 
of Arthropoda back to common arthropodan ancestors with a 
definite number of segments and distinctly crustacean in 
character; then traces these primitive arthropods back to 
forms like the nauplius larva of Crustacea, and these in turn 
