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 hlrsulu Barrande (Pages 128, 1'29) 



FiGUKE 1. — Protaspis stage. 



FiGUKE 2. — Cephalon ; nepionic stage of individual having two free 

 thoracic segments. 



FiGUKK '<i. — Cephalon; later nepionic stage of individual luiving eight 

 free tiioracic segments. 



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



Ontogeny of Dalmanites socialis Barrande (Pages 128, 129) 



Figure 5. — Protaspis stage. 



Figure 0. — Cephalon ; nepionic stage of individual having three 

 free thoracic segments. 



Figure 7. — Cephalon; nepionic stage of individual having seven 

 free thoracic segments. 



Figure 8. — Cepludon of adult. (Figures 5-8, after Bai'rande.) 



IIyi-oparia (Pages 134-138) 



FiGUi-.K !). - Cephalon of Agnostus ) Agnostida.. 



Figure 10. — Cephalon of Microuiscus ^ ° 



Figure 11. — Cephalon of Ilarpes )- Harpedidae. 



Fi(iURE 12. — Cei)halon of 'Jrinuc/cus ? rp • „ i • i^ 

 ,, ,., /- 1 I .• . > Innucleidfe. 



l^iGURE lo. — Cephalon ot Avipi/.r ^ 



Opisthoparia (Pages 138-152) 



Figure 14. - Cephalon of Atops ) Conocoryphidse. 



PiGURE 15. — Cephalon 01 tonncoryplie ^ -"^ 



Figure 16. — Cephalon of Ptychopuria \ Qigiijjfg 



Figure 17. — Cei)halon of O/c/nw f 



Figure 18. — Cephalon of Asap/nis / A.sai.hidfe. 



Fkujre 19. — Cephalon of IlUtnux \ "^ 



Figure 20. — Cephalon of Proi'ttis |. Proetid.io. 



Figure 21. — Cephalon of Brontem \ Broiddda". 



Figure 22. — Cephalon of fAchas ^-Licliadida-. 



Figure 23. — Cephalon of Acidaspis }- Acidaspidaj. 



Proparia (Pages 152-157) 



Figure 24. — Cephalon of Placnpnna } i,]„(>rinurida!. 



Figure 25. — Cephalon of /?"r?-/;()/n/.s- \ 



Figure 26. —Cephalon of Cahpnvipur ? (^v^]yn-,„i,>iiiajR. 



Figure 27. — Cephalon of DipUnmi S ' ' 



Figure 28. —Cephalon of Cheirurux (Eccnptorhrilc) ^Clieirurida\ 



Figure 29. — Cephalon of Dnlmnnitpx \ 



Figure 30. — Cephalon of Ddlmaiiitfs 



Figure ;?1. — Cephalon of Chusmops - i'hacoi)ida). 



Figure 3?. — Cephalon of . I ra.s/r 



Figure ."53. — Cephalon of Phacops J 



