PLATE LXV. 



Page. 

 Fig. 1. Arionellus /en's 462 



1. Central portions of head of type specimen, and side outline, x 4. 



Fig. 2. Arionellus sp. undet 463 



2. Figure of specimen referred to in text. 



Fig. 3. Zacanlltoid.es sp. undet 465 



3. Central portions of head, x 5. 



Fig. 4. Ptychoparia penfieldi 456 



4. Central portions of head. 



4a. Free cheeks, associated in same layer with fig. 4. 

 46. Associated pygidium. 

 Fig. 5. Crepicephalus texanus 460 



5. Partially restored drawing from specimens in the Middle Cambrian shales of Ala- 



bama. 

 Fig. 6. Liostracus parvus 463 



6. Central portions of head of type specimen. x6. 



Fig. 7. Ptychoparia antiquata 456 



7. Entire individual, slightly restored, x 2. 



la. Side outline of head of a variety of this species, x 2. 

 Fig. 8. Ptychoparia (E.) affinis 457 



8. Reproduction of figure of type specimen. 



Fig. 9. Solenopleura (?) weedi 464 



9. Central portions of head of type specimen. 



9a. A small head, showing same general characters as fig. 9. 



478 



