106 



PALEONTOLOGY OF NEW YORK. 



FlQ. 80. no. 81. FIO. 82. FIO. 8S. FIG. 84. FlO. 8S. 



Tig*. 80-8S. Settia AdriaU, ile Vcrncull. Consecutive sections to show internal structore of the nmbonal regions. 



Fig. 80. Oalline of tlie shell, showing location or next three sections. 

 Ft|t. 81. Section across opening of foramen, with nmbonal tabe open on the baclc. 

 Fijr. 81. Section farther down, showing attachment of the remnants or the tube to the deltidial plates. 

 Pig. 8S. Section near the hinge, showing last traces of tube adherent to the thickened deltidial plates. 

 Figs. 81, 8S. Sections from another individual, one across the foramen, the other beneath it ; showing the continuity 

 of the tube. (0.) 



V^ 



Fig. 86. 



FJO.'ST. 



no. 88. 



FlO. 89. 



Fig. 90. 



Fio. n. 



Fig. 03. 



Fio. 94. 



Fig. 99. 



FIG. 9«. Fig. 97. 



Figs. 86-98. Retzia ddrieni, de Verneuil. 



FIG. 98. 



Fig. 86. Section just below the foramen; showing the entire umbonaltubo. 



Fig. 87. Showing the adherence of the tube to the still divided and discrete deltidial plate.'*. 



Flgi.88, 89. Sections at the umbo of the brachial valve; showing the internal coalescence of the deltidial plates, 



and the open tube. 

 Fig. 90. Showing the dental lamellie, and the median septum in the brachial valve. 

 Fig. 91. Section Just above the apex of the brachial valve; showing the last traces of the deltidial plates, which are 



here free. 

 Fig. n. Section at the apex of the brachial valve. 



Fig. tt. Section cutting the posterior extension of the median and lateral lobes of the binge-plate. 

 Fig. 91. The same features further down; showing also the appearance of the teeth, and the remnants of the dental 



lamellas bordering the muscular area of the pedicle-valve, 

 ng. 9S. Section through the center of the hinge-plate; showing also the development of the dental socltets. 

 Fig. 96. Section showing the ante-median crest of the binge-plate. 

 Fig. 97. The anterior edge of the hinge-plate and its supporting septum. 

 Fig. 96. Section in fkx>nt of the hinge-plate; showing the crura and median septum. (o.) 



