REPORT OF THE STATE PALEONTOLOGIST I9O3 . 299 



Tetention of the phragmocone than to its original absence in the 

 apical portion of the shell. Since however in this species the septa 

 l)y their septal necks or funnels form a continuous ectosiphuncular 

 wall, which is thicker than the septal partitions and is readily dis- 

 tinguishable in one specimen [see pl.6, fig.3] by its light gray 

 ■color contrasting with the black matrix, we have carefully searched 

 for traces of this wall along the apical cone, without finding any 

 beyond the contraction of the shell at the beginning of the visible 

 chambering of the conch. A black conchiolinous deposit forms the 

 undoubtedly outermost wall of this preseptal conch. 



A little forward of the beginning of the cameras (about the 

 fourth camera) there occurs a distinct contraction, as in the 

 corresponding places in the species cited above. The apical por- 

 tion of this free part is slightly curved. The endosipholining, 

 which in the phragmocone is adjacent to the septal necks, extends 

 through the full length of this apical free part of the siphuncle 

 [see pl.3, fig.3]. It contrasts distinctly with the white coarse calcite 

 filling of the siphuncle and retains its full width and sharp delimita- 

 tion to within 30 mm of the apex, when it begins to thin out ; and 

 about 15 mm from the apex it has disappeared entirely, the siphuncle 

 being there wholly filled by the white sugary calcite. The extension 

 and composition of this layer of carbonaceous calcite leaves no doubt 

 that it originally formed within a membrane and thus became 

 charged with organic matter. This endosipholining is in section 

 sharply outlined by a fine black line which represents an outer 

 conchiolinous shell layer. This also extends into the chambered 

 portion of the shell, at least into its earlier part. It is this layer 

 which gives to the separate siphuncles of this species their black, 

 shiny surface. There is no' doubt that this is identical with the 

 cuticle of horny matter which incases the whole mantle and also the 

 siphuncle of Nautilus, and which also has occasionally been observed 

 enveloping the siphuncle of fossil cephalopods. 



The endosiphuncle passes unrestricted to the very apex of the 

 siphuncle, where it distinctly empties to the exterior [see pl.6, fig.3]. 

 Its last apical part (about i mm) is filled with black material which 

 appears to be the same as the matrix. This suggests that in this 



