PLATE XXV. 



Note —The letters at the close of each description of the figures indicate the locality at 

 which trie specimen figured was found, as follows : S. H. O -Soldiers' Home ; F. O.— Fauver's ; 

 H. O.— Huffman's ; B. O.— Brown's; C. O.-Centrevil^s ; T. F. O.— Todd's Fork; F. H. O.— Fair 

 Haven; E O.— Eaton, Ohio ; H. I.— Hanover, Indiana; C. A.— Collinsville, Alabama ; C. T.— Cum- 

 berland Gap, Tennessee. 



PAGE. 



Fig. 1. ORTHOCERAS (CYCLOCERAS) INCEPTUM Foerste 543 



1 u. Views of the carina after the action of strong weathering, removing part of the 



cast. The rows of pits illustrated in the two figures to the right are too regular 

 and were the result of weathering ; they represent no real structure of the shell. 



b. Views, showing position of the siphuncle. •.. A longitudinal section, showing 

 the cylindrical siphuncle at the centre, and accidental concretionary material 

 around the same. H. O. Marl. 



Fig. 2. Meristella umbonata Billings 590 



2 u. Lateral view. b. View of the brachial valve. S. H. O. 



Fig. 3. PLATYCERAS ( PLATYSTOM A ) NIAGAREN9E Hall 553 



3 a. Ordinary, immature form b. Form approaching variety plebium. S. H. O. 



Fig. 4. Eichwaldia reticulata Hall ; 594 



4. a. Brachial valve. A. Pedicle valve. F. O. 



Fig. 5. PlECTambonites TransvERSalis Wahlenberg 566 



5. Variety - reversata, Foerste. «. Pedicle valve, b. Outline, showing curvature of 



the shell. S. H O. 



Fig. 6. Atrypa marginalis Dalman 591 



6. A young brachial valve H. O. Marl. 



Fig. 7. OrThis ( plaTystrophia ) biforaTA Schlotheim 579 



7. Of the form with many plications in sinus and in fold, called reversata; pedicle 



valve. S. H. O. 



Fig. 8. Orthis ( plaTystrophia ) biforata Schlotheim 579 



8. Of the form with two plications in the.sinus and three on the fold, called Daytonen- 



■ ensis ; pedicle valve. S. H. O. 

 Fig. 9. • Atrypa marginalis Dalman 591 



S. Pedicle valve. S. H. O. 

 Fig. 10. Orthis (rhipidomella) hybrida Sowerby 584 



10. a. Brachial valve, b. Lateral view, drawn to show outline only. S. H. O. 



Fig. 11. • Orthis (dalmanella) eleganTula Dalman 581 



11. «. Brachial valve, b. Lateral view, drawn to show outline only. S. H. O. 



Fig. 12. Orthis (orthis) calligramma Dalman 572 



12. Of a type nearest to the typical forms of Hall and Clarke's redefinition of the 



genus Variety eu-orthis. «. Brachial valve, b. Pedicle valve. S. H. O. 

 Fig. 13. Orthis (Herbertella) Daytonensis Foerste 575 



13. o. Brachial valve, b. Lateral view, drawn to show outline of brachial valve only. 



c. A few of the radiating plications, d. The same slightly enlarged S. H. O. 



Fig. 14. Pterinea brisa Hall 557 



14. Fragments of the lelt valve. S. H. O. 



Fig. 15. Orthis (Herbertella ) fausta Foerste 573 



l"i. u. Brachial valve. *. Pedicle valve, c. Lateral view, drawn to show outline of shell 

 only. d. A few of the plications, slightly enlarged. S. H. O. Carrolltou Pike 

 quarry. 



Fig. 16. Orthis (Herbertella) fausta Foerste 573 



10. u. Brachial valve b Plications slightly enlarged. S. H. O. Carrollton Pike quarry, 

 now abandoned, halfway between Geo. Young's present quarry and the German- 

 town pike. 

 Fig. 17. Orthis (Dalmanella) elegantula Dalmau 581 



17, Variety parva, probably only young specimens of the species, a. Pedicle valve, b. 

 Lateral view of the same S. H. O. 



