PLATE 25 



Figs. Rhynchocamara plicata Schuchert and Cooper 



1,2,7. — Ventral, posterior, and dorsal views of exterior, 

 showing subrhynchonelloid form. 



17. — Posterior portion of ventral interior, showing spon- 

 dylium. 



18. — Dorsal interior, showing small chamber beneath beak 

 of dorsal valve, formed by union of crural plates with 

 strong median septum. This is a rhynchonelloid fea- 

 ture and places this form and its congeners with the 

 Rhynchonellacea. 

 Ordovician (Stones River, Central Is.), near Mur- 

 freesboro, Tenn. Cotypes. Cat. No. S 2035. x 1.5. 



Camerella hemiplicata (Hall) 



3, 4, 6, 10. — Posterior, ventral, lateral, and dorsal views of 

 a somewhat crushed specimen, showing strongly con- 

 vex dorsal valve and relatively smaller ventral valve. 

 X 1. 

 43. — ^Thin slice of interior, showing spondylium, cruralium, 

 and crural als. x ca. 4. 

 Ordovician (Trenton), Lowville, N. Y. Cat. Nos. 

 S1593 and SI 597 (fig. 43). 

 9, 1 1 . — Ventral and anterior views, showing sulcus, x 1 . 

 16. — Ventral view of a young shell, showing median sep- 

 tum. X 1. 

 24. — Section of interior of a rather young form, showing 

 spondylium and cruralium. A faint crural alar exten- 

 sion can be seen, x 4. 

 Ordovician (Trenton), Watertown, N. Y. Cat. 

 Nos. S1588 (figs. 9, 16), S 1600 (fig. 11), and 

 S1603 (fig. 24). 



Camerella volborthi Billings 



5. — Ventral interior, with prominent spondylium. 



Ordovician (Black River), Paquette Rapids, Ottawa 

 River, Quebec. Cat. No. 1594S, x 1.5. 

 20, 21. — ^Ventral and dorsal views of a young specimen. 

 27, 30. — Lateral and dorsal views of a larger individual. 

 These specimens were among Billings' types. 

 Same horizon and locality as above. Cat. Nos. 

 1 148b, 1 148a, Nat. Mus. Canada, x 2. 

 22, 28, 29. — Lateral, dorsal, and posterior views of the 

 same individual, showing exterior. Cf. C. hemifli- 

 cata, especially fig. 9. 

 Same horizon and locality as above. Nat. Mus. 

 Canada, x 2. 



Figs. Camerella scofieldi (Winchell and Schuchert) 



8, 12, 13. — Ventral, posterior, and dorsal views of exterior. 

 Ordovician (Galena), near Cannon Falls, Minn. 

 Cat. No. 8 1 592. x 1. 



Anastrophia vernemli (Hall) 

 14, 15, 19. — Lateral, posterior, and dorsal views of exterior, 

 showing implantation of ribs in fold, x 1. 

 Devonian (Helderberg), near Clarksville, N. Y. 

 Cat. No. S 1619. 



33, 36. — Dorsal interior, showing partial side and dorsad 



views. Fig. 36 shows musculature well, x 1.5. 



34, 35. — Spondylium in partial side and direct or dorsad 



view. Septum supports spondylium for nearly its 

 whole length, x 1.5. 

 38, 39. — Different views of the same specimen, showing to 

 perfection crural ala:, supporting plates, and muscula- 

 ture. X 1.5. 

 Devonian (Helderberg), Clarksville, N. Y. Cat. 

 No. S 1640. 

 41. — Interior of both valves in conjunction, x 1.5. 

 42. — Same view of another specimen, in which the sides 

 of the spondylium have grown over, restricting the 

 area of muscular attachment to a narrow opening. 

 xl.5. 

 Devonian (Helderberg), near Clarksville, N. Y. 

 Cat. Nos. S 1632 (fig. 41) and S 1631. 



Anastrophia deflexa (Sowerby) 



40. — Thin section, showing arrangement of internal plates. 

 There are lateral alas on the spondylium as well as 

 in the dorsal valve. 



Silurian (Wenlock), Dudley, England. Cat. No. 



S1623. xca. 4. 



Parastrophinella ops (Billings) 



23,25,26. — Ventral, posterior, and dorsal views of ex- 

 terior. 

 Silurian (Chicotte),Anticosti. Cat. No. S 1608. x 1. 



Liocoelia proxima (Barrande) 

 31, 32, 37. — Ventral, dorsal, and lateral views of exterior 

 of this smooth rhynchonellid. See t. fig. 36. 

 Silurian (Etage Eej), Kolednik, Bohemia. Cat. 

 No. S 1696. X 1. 



244 



