PLATE VII—Continued. 
Genus HEMIPEONITES, Pander. 
Page 238. 
Hemipronites, sp. ? 
Fig. 20. A-view of the pedicle-valve, the cardinal area being in the plane of vision. The area of the op¬ 
posite valve and the deltidia of both valves are shown. X 2. 
Fig. 21. A cardinal view of the same specimen ; showing the characteristic contour upon which is based 
the separation of these forms from Clitambonites. X 2. 
Fig. 22. A specimen cut horizontally across the umbonal region of the pedicle-valve ; showing the united 
dental lamellae supported by a median septum. X 2. 
Lower Silurian. Russia. 
Genus CLITAMBONITES, Pander. 
Page 233. 
Clitambonites adscendens, Pander. 
Fig. 23. A cardinal view, giving the subpyramidal contour characterizing this genus; showing also the 
foramen in the deltidium. X 2. 
Fig. 24. A pedicle-valve with the apex cut away; showing the peculiar internal structure of this valve. X 2. 
Lower Silurian. Russia. 
For further illustration, see Pander, Beitrage zur Geogn. russ. Reiches, plates xvii, xviii, and de 
Verneuil, Geologie de la Russie et des Mont, de l’Oural, plate xii, fig. 3. 
Clitambonites (Ortiiisina) anomala, Schlotheim. 
Fig. 25. A view of the pedicle-valve; showing the great retrorsion of the apex, the high cardinal area of 
the pedicle-valve, and the perforated deltidium ; and also the area and deltidium of the oppo¬ 
site valve. (After de Verneuil, Geol. Russ, et des Mont, de 1’Oural, plate xii, fig. 2 b.) 
Fig. 26. The interior of the brachial valve; showing the extreme development of the cardinal area and 
deltidium, the latter entirely obscuring the cardinal process; the character of the muscular 
and vascular scars is also distinctly seen. (After Davidson.) 
Fig. 27. The interior of a pedicle-valve. (After Davidson.) 
For further illustration, see de Verneuil, Geol. Russ, et des Mont, de l’Oural, plate xii, fig. 2. 
Clitambonites plana, Pander. 
Fig. 28. The interior of the pedicle-valve ; showing the radiating ridges beneath the spondylium. (After 
Davidson, Introd. Foss. Brach., plate viii, fig. 153.) 
Genus SCENIDIUM, Hall. 
(See Plate VIIa.) 
Page 241. 
SCENIDIUM PYRAMID ALE. Hall. 
(See Plate VIIa, figs. 29, 30.) 
Fig. 29. View Of the type-specimen ; showing the open delthyrium in each valve. X 2. 
Fig. 30. A cardinal view; Showing the size of the areas of the two valves and character of the delthyrium. 
X 2. 
Niagara group. Lockport, IV. Y. 
SCENIDIUM INSIGNE, Hall. 
Fig. 31. A view of the brachial valve; showing the concave plate (d) in the delthyrium of the pedicle- 
valve. X 8. 
Fig. 32. The opposite side of the same specimen, pedicle-valve. X 8. 
Fig. 33. A cardinal view of conjoined valves ; showing the concave plate in the delthyrium (d), the hinge- 
ljl plate (a) and the median septum (s). X 8. 
Fig. 34. The interior of the brachial valve ; showing the elevated hinge-plate and the prominent median 
septum. X 8. 
Fig. 35. The interior of a pedicle-valve with an open delthyrium. X' 8. 
Lower Helderberg group. Near Clarksville, N. Y. 
