444 
EXPLANATION OF PLATES, 
FIGURE, 
40, 
4]. 
42. 
45. 
. Arca (Scapharea) ineequivalvis, Brug., . 
. Arca Senilia) senilis, Linn. W. Africa, 
. Scapharea pinna, Benson. India, 
. Pectunculus Delesserti, Reeve. Hab.? 
. Allopagus Leanus, Desh. Eocene; Paris Basin, 
. Yoldia. Enlarged. The internal organs are repre- 
. Macrodon Hirsonensis, d’ Arch. Oolite; England, 
. Parallelopipedon tortuosum, Lam. China, 
. Cucullea concamerata, Mart. Philippines, 
. Limopsis complanata, d’Orb. Cret.; Europe, 
. Limopsis alter, Deshayes. Paris Basin, : 
. Trigonoceelia inzequivalvis, d’Orb. Eocene; France, 
- Nucinella miliaris, d’Orb. Eocene; Europe, 
. Arca (Plagiarca) Garolinensis, Conr. Cret.; N. Carolina, 
Arca (Barbatia) velata, Sowb. Lord Hood’s Is., 
Arca (Acar) donaciformis, Reeve. W. Indies, 
Area (Calloarca) alternata, Reeve. W. Columbia, 
Area (Anomalocardia) auriculata, Linn. W. Coast 
Cent. Am., 
47. Arca (Argina) pexata, Say. United States, 
51. Arca (Nemodon) Eufalensis, Conr, Kocene; Ala., 
55. Nucunella Nystii, Galeotti. ‘Tertiary ; Belgium, 
PLATE 127. 
. Schizodus Schlotheimi, Geinitz. Permian; Europe, 
. Myophoria decussata, Munst. Trias; Ty rol, 
59. Remondia furcata, Gabb. Cretaceous ; California, 
sented as seen through the nS on the removal of 
the right valve. a,a,adductors; p, p, pedal muscles; 
l, ligament; g, gills : Ss. siphons (much contracted) ; 
t,c, labial palpi and appendages ; 7, intestine ; /, foot ; 
x“, w, lateral muscles of the foot ; m, pallial line, 
. Naculites ovatus, Sowb. Silurian; England, 
64. Cytherodon appressus, Conr. Ham. Gr.; N. Y., 
: Arca (Polynema) lineata, Conr. Cret.; N. Carolina, 
67. Arca (Striarca) centenaria, Say. Miocene; Va. 
. Area (Litharea) lithodomus, Sowb. West Columbia, 
. Arca (Isoarca) texta, Munst. Fossil. Corallian; 
. 255 
Germany, ; ; 
T1. Arca (Carbon area) sibbosa, M. and W. Carb.; Ills. 
81. Macrodon (Cucullaria) heterodonta, Desh. Eocene; 
Paris Basin, 
PAGE. 
. 253 
. 254 
. 254 
. 254 
. 254 
. 255 
. 255 
. Arca (Nemoarca) cretacea, Conr. Cret.; New Jersey, 
. Arca (Lunarca) costata, Gray, 
254 
. 209 
256 
. 256 
. 258 
. 209 
246 
. 246 
247 
Bs 
254 
255 
. 255 
. 256 
. 256 
. 259 
. 259 
259 
. 260 
254 
: : : : . 256 
. Arca (Breviarca) perovalis, Conr. Cret.; N- Carolina, 
3. Lyrodesma pulchella, Hall. Hudson River Gr.; N.Y., 
257 
258 
