PLATE VI— Continued. 



RIIIPJDOMELLA, CEhlekt. 



Page 20«. 



Orthis Oweni. Sp. IIOV. 



(See Sujijilemeiil Cor de.sc;riylioii.; 

 Fig. 19. The exterior of a bi'achial valve. 

 Figs. 20, 21. Interiors of pedicle and brachial valves, respectively. 



" Knobstone g-roup" of Owen, = ag-e of the Waverly. Buttoririnould Knohs, Kfiitucky. 



SCHIZOPHORIA, King. 



P.-ige 2J1. 

 OinilLS CARIXATA, Hilll. 



Pig-. 22. An internal cast of a peiliele-valve ; showing the charactei- of the muscular ai-ea, at the anteiior- 

 margin of which are seen traces of the vascular sinuses. 

 Chemung group. Near Painted Pout, N. T. 

 For fnrthei' illustration, see Palaeontology of New Yoi-k, Volume IV, jilate viii, figs. 30-32. 



Ortiiis Swallovi. ILill. 



Figs. 23, 24. The exterior and inferior of the pedicle-valve. 



Burlington limestone. Burlington, Iowa. 



Okthis Tllliensis, Hall. 



Figs. 25, 26, 27. Three views of a noi-mal individual; showing the great convexity of the brachial valve 



and the shallow pedicle-valve. 

 Fig. 28. An internal cast of the lirachial valve; showing the (juadriiple muscular impression and the piin- 



cipal vascular trunks. At y is the tilling of the ro.stral cavity of the 0))posite valve. 

 Fig. 29. An internal cast of the pedicle-valve. 



TuUy limestone. Keuka Lake, N. Y. 

 For further illustration, see Paleontology of New York, Volume IV, plate vii, tig. 5. 



Orthis propinqua, Hall. 



Fig. 30. An internal cast of the bi'achial valve. The subdivision ami the coui-se of the vascular sinuses 

 are vei'y shai'ply retained. 



Corniferous limestone. Avon, N. Y. 

 For further illustration, see Palaeontology of New York, Volume IV, plate v, fig. 3. 



Orthis impressa, Hall. 



(See Plate VI A, tigs. 2ti, 27.) 

 Fig. 31. An internal cast of the pedicle-valve; showing the subdivisions of the muscular ai-ea, and the un- 

 usual arrangement of the ^-ascular sinuses. 

 Chemung groui^. 

 For further illustration of this species, see Palaeontology of N.Y., Volume IV, pi. viii, figs. 11-19. 



ORTHOSTiROPHIA, Hall. 



Page 109. 



Orthis strophomenoides, Hall. 



(See Plate Va, Hgs. 24-27.) 



Fig. 32. The exterior of an imperfect brachial valve. 



Fig. 33. An internal cast of the pedicle-valve ; sliowing the vei-y small muscular ai-ea. the ovarian mark- 

 ings in the umbo-lateral regions, and the vasculai- sinuses over the pallial region. 



Fig. 34. An internal cast of the brachial valve, retaining the impression of the simple ca]-dinal process, and 

 showing the four sharply defined adductor scars, the ovarian markings and the ramified vascu- 

 lar sinuses. 



