PLATE XIc. 
(Figures 1-3, 5-9,13,14, 17, 18, 20-22 by K. P. Whitfield; 4,10-12, 15,16,19, 25-28 by E. Emmons; 23, 24 by C. E, Beecher; 
29-39 copies.) 
Legend. F. Foramen, d. Dental lamellae. 
ps. Deltidium. a. Anterior adductors, 
c. Crura. a / . Posterior adductors, 
j. Cardinal process. r. Diductors. 
Genus TRIPLEGIA, Hall. 
Page 269. 
Triplecia extans, Emmons. 
Fig. 1. The brachial valve of an individual of average dimensions. 
Fig. 2. An anterior view of the same. 
Fig. 3. A cardinal view of the same. The delthyrium, which is here represented as open, is obscured in 
the specimen. 
Trenton limestone. Lowville, N. Y. 
Fig. 4. The cardinal area of the pedicle-valve; showing the apical foramen and the convex deltidial 
covering. 
Trenton limestone. Carlton Island, N. Y. 
Fig. 5. A cardinal view of a brachial valve ; showing the bifurcated cardinal process extending into 
the matrix. 
Figs. 6, 7. Anterior and posterior views of a normal individual, the latter showing the impressions of the 
dental plates of the pedicle-valve. X 2. 
Trenton limestone. Middleville, N. Y. 
Triplecia nucleus, Hall. 
Figs. 8, 9. Cardinal and profile views of a normalindividual, the former showing the foramen and deltid¬ 
ium of the pedicle-valve. X 2. 
Trenton limestone. Middleville, N. Y. 
Triplecia spiriferoides, McCoy. 
Fig. 10. An internal cast of the brachial valve. 
Fig. 11. A cardinal view of the same specimen ; showing the impressions of the crura (c) and of the bifur¬ 
cated cardinal process. 
Caradoc sandstone. North Wales. 
Triplecia Ortoni, Meek. 
The interior of the pedicle-valve ; showing the narrow area and much thickened teeth. 
The exterior of a brachial valve. ( 
Cardinal view of a specimen having the valves in conjunction ; showing the cardinal area, fora¬ 
men and deltidium. 
Interior of the cardinal region of conjoined valves ; showing their mode of articulation. 
Profile of the apical portion of the brachial valve ; showing the curvature of the cardinal process. 
The central cardinal portion of an old and thickened brachial valve. The tips of the cardinal 
process and of one of the crura have been broken. 
The external cardinal area of conjoined valves.' X 3. 
Posterior view of the cardinal process; showing the grooves on the outer face of its branches. 
Inner view of the same feature in a younger shell. 
Clinton group. Dayton, Ohio. 
For other illustrations, see Palaeontology of Ohio, Volume I, plate xv, figs. 1 a-k. 
Triplecia insularis, Eichwald. 
Fig. 21. Posterior view of an internal cast of the conjoined valves; showing, in the brachial valve, the im¬ 
pressions of the antertor and posterior adductors, the crura and cardinal process, and, in the 
pedicle-valve, the extent of the dental lamellae. 
Caradoc sandstone. Ty-Isaf, Wales. 
Fig. 12. 
Fig. 13. 
Fig. 14. 
Fig. 15. 
Fig. 16. 
Fig. 17. 
Fig. 18. 
Fig. 19. 
Fig. 20. 
