I'L.VTE V A— Continued. 



Okthis pokcata, McCoy. 

 Figs. 20, 21. Bi-achial ami profile views of an average example ; showing the rotundity of the brachial valve 

 and the resupination of the opposite beak. 



Mi<l(lle Silurian. Junction Cliff, Anticosti. 

 For further illustration, see Davidson, Silurian Brachiopoda, plate xxxii, figs. 12-20. 



ORTHOSTKOPIIIA, Hall. 



Page 199. 



Ortiiis Halll Saffbrd (? = 0. slroph&menoides, 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. Pen-y county, Tennessee. 



Orthis strophomenoiues, Hall. 



See Plate VI, fig.s. 82-34. 



The exterior of a brachial valve. 



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.) 

 The interior of a lirachial valve ; showing the character of the cai'dinal process, mnsculai- area, 



ovarian and vascular markings. 

 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 Helderbei-g group Near Clarhsville, N. Y. 

 Foi- further illustration, see PaUeontology of New York, Volume III, plate xxiii, fig. 7. 



PL^SIOMYS, NOM. NOV. 



Page 1915. 



Orthis deflecta, Conrad. 



Fi"-s. 28, 29. The extei-ior of the brachial and pedicle-valves. 



Fi"-. 30. A cardinal view of the .same specimen ; showing the elevation of the area, the convex deltidium, 

 and the convexity of the bi-achial valve. 



Trenton horizon. Dixon, Illinois. 

 For further illustration, see Palfeontology of New York, Volume I, plate xxxiB, fig. 5. 



Orthis loricula, sp. nov. 



Fig. 31. The cardinal area of the pedicle-valve ; showing the deltidiinn. 



Fig. 32. The exterior of the pedicle-valve. 



Fig. 33. The interior of the brachial valve. The delthyrium is tilled by a callosity which also supports 



the crnriil plates and the linear cardinal pi-oce.ss ; the deltidinra is also present in an incipient 



condition. 

 Fig. 34. The interioi- of the pedicle-valve ; showing the character of the muscular area, ovarian mai'kings, 



etc. 



Galena limestone. Fountain, Minne-iota. 



Orthis Holstoni, Safford. 



Fig. 35. Profile of the ty|ie specimen. 



Fig. 3t>. (."ardinal view of the same; showing the wide delthyrium and elevated area of the jiedicle-valve. 



Fig. 37. A view of the brachial valve of the same specimen. 



Trenton horizon. iVear Knoxville, Ttnnesee. 



Orthis Saffordi, sj). nov. 



Figs. 38, 39, 40. Thi'ee views of the exterior of a specimen ; showing its general form and the character of 

 its surface markings. 



Trenton horizon. Near Knoxville, Tennessee. 



