444 EXPLANATION OF PLATES. 



40. Area (Barbatia) velata, Sowb, Lord Hood's Is., . 253 



41. Area (Acar) donaciformis, Reeve. W.Indies, . . 254 



42. Area (Calloarea) alternata, Reeve. W. Columbia, . 254 



43. Area (Anomalocardia) auriculata, Linn. W. Coast 



Cent. Am., 254 



44. Area (Scapharca) inasquival vis, Brug., . . . . 254 



45. Area Senilia) senilis, Linn. W. Africa, . . . 255 



46. 47. Area (Argina) pexata, Say. United States, . . 255 



48. Area t^Nemoarca) eretacea, Conr. Cret. ; New Jersey, 254 



49. Area (Lunarca) eostata, Gray, ..... 255 



50. 51. Area (Nemodon) Eufalensis, Conr. Eocene; Ala., 256 



52. Scapharea pinna, Benson. India, .... 256 



53. Pectvinculus Delesserti, Reeve. Hab. ? . . . 258 



54. 55. Nucunella Nystii, Galeotti. Tertiary ; Belgium, . 259 



Plate 127. 



56. Schizodus Schlotheimi, Geinitz. Permian; Europe, 246 



57. Myophoria deeussata, Munst Trias; Tyrol, . . 246 



58. 59. Remondia furcata, Gabb. Cretaceous ; California, 247 



60. Allopagus Leanus, Desh. Eocene; Paris Basin, . 197 



61. Yoldia. Enlarged. The internal organs are repre- 



sented as seen through the mantle, on the removal of 

 the right valve, a, a, adductors; p, p, pedal muscles; 

 Z, ligament ; g, gills ; s, siphons (much contracted) ; 

 t, c, labial palpi and appendages ; i, intestine ; /", foot ; 

 X, X, lateral muscles of the foot ; «i, pallial line, . 249 



62. Naculites ovatus, Sowb. Silurian; England, . . 251 

 63,64. Cytherodon appressus, Conr. Ham. Gr. ; N. Y., . 259 

 65. Area (Polynema) lineata, Conr. Cret. ; N. Carolina, 254 

 66,67. Area (Striarca) centenaria, Sa3\ Miocene; Va. . 254 



68. Area (Litharea) lithodomus, Sowb. West Columbia, 254 



69. Area ( Isoarca) texta, Munst. Fossil. Corallian ; 



Germany, ......... 255 



70. 71. Area (Carbonarca) gibbosa, M. and W. Carb.; Ills. 255 



72. Macrodon Hirsonensis, d'Arch. Oolite; England, . 255 



73. Parallelopipedon tortuosum, Lam. China, . . 256 



74. Cucullsea concamerata. Mart. Philippines, . . 256 



75. Limopsis complanata, d'Orb. Cret. ; Europe, . . 259 



76. Limopsis alter, Deshayes. Paris Basin, . . . 259 



77. Trigonocoelia ineequivalvis, d'Orb. Eocene; France, 259 



78. Nucinella miliaris, d'Orb. Eocene; Europe, . . 260 



79. Area (Plagiarca) Carolinensis, Conr. Ci-et.; N.Carolina, 254 

 80,81. Macrodon (Cucullaria)heterodonta, Desh. Eocene; 



Paris Basin, . 256 



82. Area (Breviarca) perovalis, Conr. Cret.; N- Carolina, 257 



83. Lyrodesma pulchella, Hall. Hudson River Gr. ; N.Y., 258 



