REPORT OF THE STATE PALEONTOLOGIST I9O3 



309 



e<ss 



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zontal position has changed to a vertical one. A horizontal section 

 through the block containing this turn has been made and the rock 

 polished down sufficiently to expose the turn [fig.4]. Figure 5 

 shows the front of the next block, which is identical with the posterior 

 section of figure 4. Here the endosiphuncle has become a very nar- 

 row cylindric tube (endosiphotube) sharply limited by a black con- 

 chiolinous wall. It lies somewhat laterally to a broad, dark gray 

 brown belt of organic lime carbonate, through which the walls of the 

 large crystals of the siphuncle fill- 

 ing pass, though retaining the 

 organic coloring matter in its 

 original distribution. A split is 

 noticeable in the upper part, as 

 if the band here consisted of two 

 lamellae. Text figure 10 repre- 

 sents this condition of the endo- 

 siphuncle. The endosiphotube is 

 now the only remaining organ 

 with distinct conchiolinous walls 

 and the endosiphocoleon is re- 

 duced to a dark band of organic 

 lime carbonate, a transverse 

 median line of which indicates 

 Its former composition of two 

 amellae. 

 On the other side of the block 



[fig.6, 7.5 mm farther posteriorly] to show the relation of the wings M to the 



. endosiphosheaths [ess]. Endosiohocoleon cut 



the endosiphotube has retamed through major axis 

 the same diameter as in the preceding section, though its shape has 

 changed from circular to semicylindric ; the endosiphocoleon has not 

 diminished in size, but has become considerably lighter in color and 

 more indistinct in outline, specially in the middle part, while the ends 

 have remained colored slighth^ stronger and are wider so that 

 the section assumes somew^hat the shape of a dumb-bell. The 

 median line, observed in the preceding section, has disappeared, 

 but there remain two darker spots in the center of the end balls 



Fig. 14 Diagrammatic section of siphuncle 

 elat 



