PLATE 27 



Figs. Virgiana barrandei (Billings) 



1,6,7, 1 6. — Lateral, ventral, dorsal, and posterior views 

 of a large specimen. 



Silurian (Becscie River), Becscie River, Anticosti. 



Cat. No. S 1668. x 1. 



Platymerella aff. manniensis Foerste 

 2, 3, S, 11. — Ventral, dorsal, posterior, and lateral views of 

 exterior. 

 Silurian (Alexandrian, Sexton Creek), Belleview, 

 Calhoun Co., m. Cat. No. SI 84 5. i 1. 



Pentamerus cf. oblongus Sowerby 

 4. — Internal septa in a specimen broken through the 

 middle. 

 8, 12, 18. — Lateral, dorsal, and ventral views of exterior. 

 10. — Dorsal exterior of a young specimen. 



Silurian (Clinton), Rochester, N. Y. Cat. Nos. 

 S1805,S 1833 (fig. 10), and 8 1851 (fig. 4). x 1. 



Figs. Pentamerus aff. oblongus Sowerby 



17, 19. — Posterior and dorsal views of an internal mold, 

 showing septa. 

 Silurian (Niagaran), near Richmond, Ind. Cat. 

 No. S 1808. xO.5. 



Pentamerus cf. cylindricus Hall and Whitfield 

 9, 1 5. — Ventral and dorsal views of an internal mold, show- 

 ing impressions of septa. 

 Silurian (Niagaran), Yellow Springs, Ohio. Cat. 

 No. SI 826. xO.5. 



Pentameroides subrectus (Hall and Clarke) 

 13, 14. — Internal molds of dorsal and ventral interiors of 

 the same specimen. Note single septum in dorsal 

 valve, 



Silurian (Maquoketa), Jones Co., Iowa. Cat. No. 



S1848. x 1. 



Holorhynchus giganteus Kiaer 

 20. — Dorsal view of exterior. This genus is interesting 

 for its possession of a free spondylium. 

 Silurian (zone 5b), Sandviken, Boerum, Norway. 

 Cat. No. S 2135. x 2. 



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