PLATE II 

 DEVELOPMENT AND CLASSIFICATION OF TRILOBITES 



Figures are approximately of the same size to facilitate comparison. 

 The dorsal areas of the free-cheeks are shaded. 



Ontogeny of Sao Ursula Barrande (Pages 128, 129) 



FIGURE 1. Protaspis stage. 



FIGURE 2. Cephalon ; nepionic stage of individual having two free 

 thoracic segments. 



FIGURE 3. Cephalon; later nepionic stage of individual having eight 

 free thoracic segments. 



FIGURE 4. Cephalon of adult. (Figures 1-4, after Barrande.) 



Ontogeny of Dalmanites socialis Barrande (Pages 128, 129) 



FIGURE 5. Protaspis stage. 



FIGURE 6. Cephalon ; nepionic stage of individual having three 

 free thoracic segments. 



FIGURE 7. Cephalon; nepionic stage of individual having seven 

 free thoracic segments. 



FIGURE 8. Cephalon of adult. (Figures 5-8, after Barrande.) 



HYPOPARIA (Pages 134-138) 



FIGURE 9. Cephalon of A qnostus ) . ,., 

 FIGURE 10. Cephalon of Microdiscus \ Agno 

 FIGURE 11. Cephalon of Harpes }- Harpedidse. 



FIGURE 12. Cephalon of Trinucleus 1 T , n . , 

 FIGURE 13. - Cephalon of Ampyx \ Trmucleidae. 



OPISTHOPARIA (Pages 138-152) 



FIGURE it. -Cephalon of ^onocoryphe | Conocoryphidse. 

 FIGURE 16. Cephalon of Ptychoparia > ni . , 

 FIGURE 17. Cephalon of Olenus Ule 18e * 



FIGURE 18. Cephalon of Asaphus 

 FIGURE 19. Cephalon of Illcenus 

 FIGURE 20. Cephalon of Proetus 

 FIGURE 21. Cephalon of Bronteus 

 FIGURE 22. Cephalon of Lichas 



Asaphidse. 



Proetidse. 

 Bronte idae. 

 Lichadidse. 



FIGURE 23. Cephalon of Acidaspis j- Acidaspidse. 

 PROPARIA (Pages 152-157) 



FIGURE 24. -Cephalon of Placoparia > Encrinuridffi . 



FIGURE 2o. Cephalon of Encnnurus > 



FIGURE 26. Cephalon of Calymmene ) Calvmmenidse 



FIGURE 27. Cephalon of Dipleura \ J 



FIGURE 28. Cephalon of Cheirurus (Eccoplocheile) }-Cheiruridse. 



FIGURE 29. Cephalon of Dalmanites 



FIGURE 30. Cephalon of Dalmanites 



FIGURE 31. Cephalon of Chasmop* 

 FIGURE 32. Cephalon of A caste 

 FIGURE 33. Cephalon of Phacops 



Phacopidse. 



