PLATE V A—Continued. 
Orthis porcata, McCoy. 
Figs. 20, 21. Brachial and profile views of an average example ; showing the rotundity of the brachial valve 
and the resupination of the opposite beak. 
Middle Silurian. Junction Cliff, Anticosti. 
For further illustration, see Davidson, Silurian Brachiopoda, plate xxxii, figs. 12-20. 
ORTHOSTEOPHIA, Hall. 
Page 199. 
Orthis Halli. Stiffen'd (? = 0. strophomenoides , Hall). 
Fig. 22. A view of the pedicle-valve. 
Fig. 23. A cardinal view of the conjoined valves of the same specimen. 
Lower Helderberg group. Perry county, Tennessee. 
Orthis strophomenoides, Hall. 
' , See Plate VI, figs. 32-34. 
Fig. 24. The exterior of a brachial valve. 
Fig. 25. A cardinal view of the same specimen; showing greater convexity than the preceeding species. 
(The relative position of the valves as represented in the figures 23 and 25 is reversed.) 
Fig. 26. The interior of a brachial valve; showing the chai’acter of the cardinal process, muscular area, 
ovarian and vascular markings. 
Fig. 27. The interior of the opposite valve. The muscular area is greatly thickened and is divisible into 
the adductor and diductor elements; the vascular sinuses are also very distinct. 
Lower Helderberg group Near Clarksville, N. T. 
For further illustration, see Palseontolog-y of New York, Volume III, plate xxiii, fig. 7. 
PLiESIOMYS, nom. nov. 
Page 196. 
Orthis deflecta, Conrad. 
Figs. 28, 29. The exterior of the brachial and pedicle-valves. 
Fig. 30. A cardinal view of the same specimen ; showing the elevation of the area, the convex deltidium, 
and the convexity of the brachial valve. 
Trenton horizon. Dixon, Illinois. 
For further illustration, see Palaeontology of New York, Volume I, plate xxxiB, fig. 5. 
Orthis loricula, sp. nov. 
Fig. 31. The cardinal area of the pedicle-valve ; showing the deltidium. 
Fig. 32. The exterior of the pedicle-valve. 
Fig. 33. The interior of the brachial valve. The delthyrium is filled by a callosity which also supports 
the crural plates and the linear cardinal process ; the deltidium is also present in an incipient 
condition. 
Fig. 34. The interior of the pedicle-valve ; showing the character of the muscular area, ovarian markings, 
etc. 
Galena limestone. Fountain, Minnesota. 
Orthis Holstoni, Safford. 
Fig. 35. Profile of the type specimen. 
Fig. 36. Cardinal view of the same ; showing the wide delthyrium and elevated area of the pedicle-valve. 
Fig. 37. A view of the brachial valve of the same specimen. 
Trenton horizon. Near Knoxville, Tennesee. 
Orthis Saffordi, sp. nov. 
Figs. 38, 39, 40. Three views of the exterior of a specimen ; showing its general form and the character of 
its surface markings. 
Trenton horizon. Near Knoxville, Tennessee. 
