PLATE VI. 



(tlgures 1-34, by K. 1'. Whiti'iki.u.) 



Legeuil. A. Cardinal area. j). Pedicle-area. 



t. Teeth. a. Anterior adiluctoi- .«(;ar.s. 



b'. Sockets. a'. Posterior aililuclor scars, 



d. Dental lamella. r. Antei'ior liiductor scars. 



c. Crura. r'. Posterior diductor scars, 



s. Median septum. v. Vascular markings, 



j. Cardinal process. o. Ovarian markings. 



RHIPIDOMELLA, CEhlekt. 



I'age 20S. 

 OrTHLS HYBRIDA, SoWt'lhy. 

 Figs. 1, 2, 3. Three views of an average individual of the American foi-m referi'ed to this species. 

 Fig. 4. The interior of the bracliial valve. The character of the diductor muscular scars is here incor- 

 rectly representeil, the imjiression being quadripartite and not Habellate. 

 Fig. 5. The interior of the pedicle-valve; showing the expanded muscular scars. 

 Niagara group. Lockport, N. Y. 

 For further illustration, see Davidson, Silurian Brachiopoda, |ilate xxvii. figs. 1-i) ; II.iLL, Palaeon- 

 tology of New York, Volume II, plate lii, tig. 3 ; Twenty-eighth Rept. N. Y. State Miis. Nat. 

 Hist., pi. xxi, tigs. 18-25. 



Okthis Penelope. Hall. 



(See Plate VI A. fig. 10.) 



Figs. 6, 7, 8. Three view.s, giving the external characters of a normal mature individual. 



Fig. 9. The interior of a l)ra(,'hi.al valve; showing the articulating apparatus. The nuisculai' area is quad- 

 ripartite rather than fiabellate. 



Fig. 10. The interior of a small pedicle-vah'e. 



Fig. 11. Similar view of an older shell. 



Fig. 12. The interior of a pedicle-valve, which shows the thickening about the mu.scular impressions, ac- 

 companying senility. 



Fig. 13. An enlargement of the surface striiE ; showing the openings of the obli(pie tubules upon the stri:e 

 and the scattered punctie. 



Hamilton group. Western New York. 

 For further illustration, see Paleontology of New York. Volume IV, plate vi, fig. 2. 



Orthis Vanuxejii, Hall. 



(See Plate VI A, figs. 7, 8.) 

 Fig. 14. An enlargement of the surface sti-iae. 



Fig. 15. An internal cast of the pedicle-valve ; showing the pedicle-scar and othei' muscular impressions. 

 Hamilton group. Cumberland, Maryland. 

 For further illustration, see Palteontology of New Y'ork, Voliune IV, plate vi, fig. 3. 



Orthis Leuco,sia, Hall. 



(.See Plate VI A, fig. 9.) 

 Fig. 16. The interior of the pedicle-valve. 



Hamilton group. IVe.Hern New York. 

 For further illustration, see Palteontology of New York, Volume IV, plate vii, fig. 4. 



SCHIZOPHORIA. Ki.xG. 



I'agr- ill. 



Oirrin.s Tioga, HtiU. 

 Fig. 17. The exterior of a brachial valve. 

 Fig. 18. An internal east of a pedicle-valve. 



Chemung group. Near Eliaira, N. Y. 

 For further illustration, see Palaeontology of New York, Volume IV, plate viii, figs. 20-29. 



