132 



PALAEONTOLOGY 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 



Fig. 111. 



Fio. llfi. 



Fig. n7. 



Fio. 118. Fig. 119. 



Figs. n*-n9. Consecutive transverse sections of Anoplotheca [Bifida) lepida, Goldfuss. (c.) 



Pig. lU. Section just below apex of pedicle-valve ; sUowing the teeth and the form of the hinge-plate or cardinal 



process. 

 Fig. 115. Section a little further forward; showing the elevation of the socket walls and the beginning of the 



median septum in both valves. 

 Fig. 116. Section at anterior edge of hinge-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 tlie 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 llil. Section along the stem of the loop and slightly back of the junction of the lateral branches ; .showing 



the articniatiou of the stem with the grooved ridge of the upi)er valve, .and the height of the medi.an 



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



amjile. 



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 



