PLATE V B—Continued* 
HETERORTHIS, nom. nov. 
Page 202. 
Orthis Clytie, Hall. 
Fig-. 20. A view of the brachial valve of the type-specimen ; showing the area and foramen of the pedicle- 
valve. 
Fig. 21. The interior of a pedicle-valve ; showing the elongate scars of the cardinal muscles and the small 
adductor impressions. 
Fig. 22. The interior of the brachial valve. The cardinal process is simple, but very high, and the crural 
plates are much elevated, terminating abruptly. Muscular area small F and obscurely quadri¬ 
partite. 
Fig. 23. The articular area of the same valve ; showing the divisions of the muscular area. X 2. 
Fig. 24. The surface ornamentation, consisting of a fasciculate grouping of the radiating striae, crossed by 
minute concentric lines. X 4. 
Trenton horizon. Near Frankfort, Ky. 
DALMANELLA, nom. nov. 
Page 205. 
Orthis Evadne. Billings. 
Fig. 25. A view of the brachial valve of the type-specimen; showing area and foramen of opposite valve. 
Fig. 26. The opposite side of the same specimen. 
“ Point Levis ; in the upper part of Limestone No. 2, Quebec group.” 
Orthis testudinaria, Dalnian. 
Figs. 27, 28, 29. Three views of a small form which may prove to be a permanent variety of the species. 
Fig. 30. The interior of the pedicle-valve of the same form. 
Fig. 31. The interior of the brachial valve. X 2. 
Trenton horizon. Minei-al Point, Wisconsin. 
Fig. 32. The exterior of the pedicle-valve of a normal individual. 
Fig. 33. The exterior of the brachial valve of a somewhat larger specimen. 
Fig. 34. A profile of the same. 
Fig. 35. The interior of a pedicle-valve; showing the character of the muscular area. 
Fig. 36. The interior of a brachial valve, retaining the articulating apophyses and the subdivision of the 
muscular area. 
Fig. 37. The central cardinal portion of a similar valve, enlarged to show with greater distinctness the 
structure of the articulating aparatus. 
Hudson River group. Cincinnati, Ohio. 
Fig. 38. The interior of a large pedicle-valve. 
Trenton limestone. Middleville, N. Y. 
Fig. 39. The interior of a brachial valve. X 2. 
Trenton limestone. Lowville, N. Y. 
