130 DESCRIPTION OF THE PLATES. 



TABLE III. 



Fig. 1. Proetus Cuvieri, Gerastos lavigatus, Gold!"., rolled up, side view. 



2. The same, extended, from above. 



3. Ci/phmpis ceratopldhalma, rolled up, side view. 



4. The same, extended from above. 



5. Aeonia diops {Calj/mene diops. Green). 



6. Phacops protuberans. 



7. Tril. Sternhergii, cephalic shield from the side. 



8. The same, from above. 



9. Olctms (jihhosus. 

 10. lUanus ijigantem. 



TABLE IV. 



Fig. 1 . Homalonofiis armatus. 



2. Phacops rotundifrons. 



3. Phacops proavus, cephalic and caudal shield. 



4. odonfocephaliis, head. 



5. conophihalmus. 



6. The same, rolled up. 



7. Phacojjs arachnoides. 



8. stell if er. 



9. caudal us. 



10. Four body rings of Homalonotus as seen in a transverse section. 



11. Four body rings of Calymene as seen in a transverse section. 



Remark. — The anterior smaller segment in these two transverse sections, 

 represents the articular fold; the posterior larger segment indicates the 

 true ring, beneath which the articular fold is hidden when the body is ex- 

 tended. In Catymene we merely perceive an acute angle at the place 

 where the two segments meet ; in Homalonotus, on the other hand, a 

 thick, perpendicularly-descending ridge. 



12. The eye of Phacops latifrons, without a horny membrane, enlarged to twice its 



natural size. 



TABLE V. 



Fig. 1. Asaphns cxpansus. 



a. Extended. 



b. Rolled up, and seen in front. 



c. Do. lateral view. 

 2. nianus crassicauda. 



a. Extended. 



Ij. Rolled up, front view. 



