NO. II LEGS OF PRIMITIVE ARTHROPODS EWING 4I 



Plate 7 



Fig. 19. The two types of tarsi found in the generalized Collembola of the 



family Poduridae : A, Achorutes; B, Podiira. 

 Fig. 20. The evolution of the two-clawed tarsus in Pauropus and its com- 

 parison with the two-clawed tarsus in Symphylella. A, B & C ; 



tarsi I, III and last tarsus of Pauropits; D, tarsus of Symphylella. 



(All views from above.) 

 Fig. 21. Vertical "optical section" of tip of tarsus I of proturan, Acercntu- 



lus barbcri. 

 Fig. 22. The evolution of the two-clawed type of tarsus in Thysanura and 



the one-clawed type in Protura. 

 Fig. 23. Dorsal view of feet of collembolan, Tomocerus arcticus, showing 



variation in claws; I, II, III = tarsi I, II and III respectively. 

 Fig. 24. Two-clawed tarsus of isopod crustacean of family Oniscidae. 



Plate 8 



Fig. 25. Lateral view of Pauropus hnxleyi showing body segmentation, chiti- 

 nized parts and specialized setae. 



Plate 9 



Fig. 26. Prothorax and neck region of Japyx bidentatus. 



Fig. 27. Dorsal view of first six segments of body of Pauropus sp. showing 

 chitinous plates. 



Fig. 28. Dorsal view of first five segments of body of Symphylella sp., show- 

 ing chitinous parts. 



Plate 10 



Fig. 29. Dorsal view of thorax of Acerentulus barbcri showing chitinous 



parts. 

 Fig. 30. Dorsal view of thorax of Japyx isabellac showing sclerites. 

 Fig. 31. Lateral view of thorax of a springtail, Isotoma sp., together with 



proximal parts of legs. 



Plate ii 



Fig. 32. Ventral view of cephalothorax of Holosiro acaroides. 



Fig. 33. Ventral view of last leg of left side of Pauropus sp. and the sclerites 

 of body segment it is attached to. 



Fig. 34. Ventral view of left half of body segment of Scutigcrella sp. show- 

 ing chitinizations. 



Fig. 35. Ventral view of left half of body segment of Hanscniclla sp. show- 

 ing chitinizations. 



Plate 12 



Fig. 36. Ventral view of left half of body segments of Symphylella sp. show- 

 ing chitinizations. 

 Fig. 2)7. Ventral view of thorax of proturan, Acerentulus barbcri. 

 Fig. 38. Ventral view of thorax of Japyx isabellae, showing sclerites. 

 Fig. 39. Lateral view of left side of mesothorax of Acerentulus barbcri. 



