PLATE XX— Continaeil. 



ANOPLIA; SUB-GEN. NOV. 



Page 309. 



Anoplia nucleata, Hall. 



(See Plate XVITa, 6gs, 17. 18.) 

 Vig. 14. Internal cast of a iiedicle-valve ; showing the impi-e.ssion of the short median septum, and the pus- 



tulose character of the pallial region. X 'i. 

 Fio- 15 The interior of a brachial valve ; showing the muscnlar impression and the pustulose surface. 



"' ' The cardinal process is bilobed, hot is probably shorter than is noraial for the species. X 3. 

 Fig. 16. The exterior of the brachial valve; showing the smooth surface. X 3. 



Oi-iskany sandstone. Jones comity, Tllinois. 

 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 peneti-ate to the external surface. X 6. 

 Oriskany sandstone. Columbia county, N. Y. 



CHRISTIANIA, gen. nov. 



Page 298. 



Chkistiania subquadeata, 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, Wilckeus. 



(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 intei-ior of a brachial valve ; showing very distinctly the division into anteiior and posterior 

 musc\ilar scars. 



Hudson River gi-oup. 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, tigureil on Plate VIII (tig. 31) ; enlarged from a gutta- 

 percha impression. The area is subdivide<l into three pairs of scars, the elongate central pair 

 being probably accessoi-y to the posterioi' adductors. X 3. 

 Waverly group. Medina county, Ohio. 



Lept.^na ? UNicosTATA, Meek aiul 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 

 LBPT.EBA. 



Hudson Rivei- group. Ohio. 



STROPHOMENA, Rafinesque (de Blainville). 



Page 245. 



Strophomena Winchelli, .sp. nov. 



(See Plaie 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. 



