FLA TE XXI. 

 Leperditia fonticola, Hall. 



Page 428. 



Figs. 1-3. Enlarged views of three different individuals, showing some variations in the propor- 

 tions and also in the nodes of the surface. 



Sfhjbbexochvs eominoeri. Hall. 



Page 425. 



Figs. 4, 5. Two views of a glabella of this species, natural size. 

 " 6. Profile view of the glabella and movable cheek of a small specimen. The figures are 



enlarged to three diameters. 

 " 7. The pygidium enlarged to two diameters. 



ACIDASPIS DANAL HaLL. 



i 



Page 423. 



Fig. 8. A specimen preserving the glabella and portions of the movable cheeks. The figure is of 

 the specimen originally described. 

 " 9. FigTire of another individual, showing some modifications in the lateral lobes of the gla- 

 bella. 



Ceravros niagarensis, Hall. 



Page 427. 



Fig. 10. The glabella and part of one of the fixed cheeks of a specimen of this species. 

 " 11. The hypostoma of this species .' from a specimen in the collection of Prof. Winchell. 



Lie has breviceps? Hall. 



Page 424. 



Fig. 12. The glabella and movable cheek of a specimen, enlarged to two diameters. 

 " 13. Figure of the internal cast of a pygidium ; natural size. 

 " 14. An enlarged figure of the lower surface of a pygidium. 



■ • Encrinvrus nerevs, Hall. 



Page 425. 

 Fig. 15. Figure of the pygidium of this species enlarged to two diameters. 



DaLMANIA VIGILANS, HaLL. 

 Page 426. 



Fig. 16. View of the head of a specimen denuded of the eyes. 

 " 17. Profile view of another specimen, preserving the cast of the eyes, the crust having been 



dissolved. 

 " 18. Cast of a pygidium of this species. 



Bronteus acamas, Hall. 



Page 422. 



Fig. 19. Cast of the glabella of this species, natural size. 

 " 20. The pygidium natuial size, but slightly restored on one margin. 



