PLATE XX—Continued. 
ANOPLIA, SUB-GEN. NOV. 
Page 309. 
Anoplia nucleata, Hall. 
(See Plate XVIIa, figs. 17, 18.) 
Fig. 14. Internal cast of a pedicle-valve ; showing the impression of the short median septum, and the pus- 
tulose character of the pallial region. X 3. 
Fig. 15. The interior of a brachial valve ; showing the muscular impression and the pustulose surface. 
The cardinal process is bilobed, but is probably shorter than is normal for the species. X 3. 
Fig. 16. The exterior of the brachial valve ; showing the smooth surface. X 3. 
Oriskany sandstone. Jones county, Illinois. 
Fig. 17. The central cardinal portion of an internal cast of the pedicle-valve ; showing the filling of the ob¬ 
lique cardinal tubes which do not penetrate*to the external surface. X 6. 
Oriskany sandstone. Columbia county, N. Y. 
CHRISTIANIA, gen. nov. 
Page 298. 
Christiania subquadrata, Hall. 
(See Plates XV and XVIIa.) 
Figs. 18, 19. Two views of the pedicle-valve ; showing its elongate form, incurvature and smooth or squam¬ 
ous exterior. X 2. 
Fig. 20. The exterior of the brachial valve, which shows the cardinal process and edges of the crural 
plates. X 2. 
Lower Helderberg group. Perry county, Tennessee. 
LEPTiENA, Dalman. 
Page 276. 
Lept^na rhomboidalis, Wilckens. 
(See Plates VIII and XVIIa.) 
Fig. 21. The deltidial area of both valves of a small individual. X 3. 
Fig. 21a. Longitudinal section of the two valves ; showing the degree of curvature. 
Fig. 22. The interior of a brachial valve; showing very distinctly the division into anterior and posterior 
muscular scars. 
Hudson River group. Cincinnati, Ohio. 
Fig. 23. The interior of a brachial valve, in which the margins of the broad posterior adductors have be- 
• come elevated into free alate extensions. X 2. 
Niagara group. Waldron, Indiana. 
Fig. 24. The muscular area of the brachial valve, figured on Plate VIII (fig. 31) ; enlarged from a gutta¬ 
percha impression. The area is subdivided into three pairs of scars, the elongate central pair 
being probably accessory to the posterior adductors. X 3. 
Waverly group. Medina county, Ohio. 
Lept,ena ? unicostata, Meek and Worthen. 
See Plate XVIIa, fig. 39. 
Figs. 25, 25a. The interior of a brachial valve and cardinal area of a pedicle-valve ; showing characters of 
Lept-ena. 
Hudson River group. Ohio. 
STROPHOMENA, Rafinesque (de Blainville). 
Page 245. 
Strophomena Winchelli, sp. nov. 
(See Plate IX, fig. 12.) 
Fig. 26. An enlargement of the muscular area of the brachial valve cited ; showing the broad posterior and 
elongate anterior scars. X 3. 
Trenton limestone. Janesville, Wisconsin. 
