EXPLANATION OF PLATE XVIII 



Pterygometopus fredricki sp. nov., page 79. 



Fig. 1. The type specimen. Mus. No. P 17024. X V2. 



Fig. 2. Dorsal view of the cephalon of the above. X 3/ 2 . 



Fig. 3. Outline drawing of a lateral view of the same showing the form of the 

 glabella. X 3/j. 



Figs. 4, 5. Dorsal and lateral views of a young specimen referred to this species, 

 in the collection of Mr. A. G. Becker. X 3. 



Pterygometopus larrabeei sp. nov., page 81. 

 Fig. 6. The holotype. Mus. No. P 11256. X V 4 . 



Fig. 7. Outline drawing of a lateral view of the same showing form of the gla- 

 bella, x 5/4. 



Fig. 8. Pygidium associated with the holotype. X S/ 4 . 



Calymene gracilis sp. nov., page 69. 

 Fig. 9. The type specimen. Mus. No. P 17065. X V 4 . 



