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 



FIG. 8. 



INSECTA 

 CRUSTACEA \ /PODA 



SYMPHYLA v\ / ^ DIPLOPODA 

 ARACHNID A ^ 



ARTHROPODA 



MALACOPODA 

 ANNELIDA 



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 Miil- 

 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 



