132 



PALEONTOLOGY OF NEW YORK. 



beginning at the beak. Figures 114, 115 show the cross-section of the 

 broad, stout hinge-plate, its convex central area and its elevated crural 

 bases; in figure 115 is a faint indication of the median ridge in the upper 

 or pedicle-valve. In figure 116 the crural bases are apparently merged 

 with the socket walls, the hinge-plate has become depressed, and its median 



S 



FtO. 111. 



FIO. 115. 



Fio. 110. 



Fig. 117 



Fio. 118. Fio. 119. 



FIU8. lU-119. Consecutive transverse sections of Anoplotheca (Bifida) IqHda, Goldfoss. (c.) 



Fig. 114. Section just below apex of pedicle-valve ; showing the teeth and the rorm of the liinge-plato or cardinal 

 process. 



Fig. IIS. Section a little ftirthor forward; showing the elevation of the socket walls and the beginning of the 

 median septum in both valves. 



Fig. lie. Section at anterior edge of liinge-plate. 



Fig. 117. Section cutting the posterior volutions of the spirals; showing the height of the septum in the brachial 

 valve and the thickened median ridge in the pedicle-valve. 



Fig. 118. Section through the loop ; showing its lateral branches and a portion of its erect, simple stem, and also the 

 grooved surface of the median ridge in the pedicle-valve. 



Fig. 119. Section along the stem of the loo|> and slightly back of the junction of the lateral branches; showing 

 the articulation of the stem with the grooved ridge of the upper valve, and the height of the median 

 septum supporting the loop. Figs. 111-118 are from the same specimen ; fig. 119 from another ex- 

 ample. 



elevation has taken the form of a low septum; in fig. 117 the median septum 

 of the brachial valve is very prominent, the median ridge of the opposite 

 valve undivided, and the lamellae of the first volution of the coils and the 

 stem of the loop are shown. This figure shows the manner in which the 

 loop is supported by the median septum ; also a portion of the vertical 

 stem of the loop, and the grooving of the median ridge in the pedicle-valve ; 

 and in fig. 119 the stem of the loop is seen to be produced to the inner 

 surface of the pedicle-valve and its apex fitted into the groove of the median 



