ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



589 



Arthropoda. 



Affinities, Origin, and Classification of Arthropoda.* — Dr. 

 A. C. Oudemans is of opinion that the group Arthropoda ought to be 

 given up ; in support of this proposal he discusses seriatim a 

 number of the sub-groups of which the larger group is at present 

 supposed to consist. 



1. The Acaroidea appear to be a special group, which ought to be 

 separated from the Arachnoidea. 



2. The Tardigrada appear to be more closely allied to the 

 Chsetopoda than to either the Arachnoidea or Acaroidea. 



3. The relations of the Scorpions, Trilobites and King-Crabs, 

 may be indicated by the subjoined table : — 



Prestwichia 



Limulus 



Scorpio 



Eurypterua 



Pterygotus 



Slimonia 



Proagnostus 



4. The Crustacea, after the removal of heterogeneous forms, are a 

 natural group, whose primitive larva is the Nauplius, which is very 

 different to the primitive larva of the Arachnoidea — Proagnostus. 



5. Dohrn has completely proved the absolutely separate position 

 of the Pantopoda. 



6. The Onychora (Peripatus) are also very distinct ; their develop- 

 ment shows that they come from animals like the Gastrula with a 



* Tijdschrift Nederl. Dierk. Vereen., i. (1886) pp. 37-56. 



