REPORT OF THE STATE PALEONTOLOGIST I9O3 297 



pl.6, fig.2]. The septal necks/ however, do not as in most ortho- 

 ceratites extend only a short distance backward, but curve first gently 

 inward, thus contracting the siphuncle slightly and just above the 

 preceding septum bend again outward, growing thicker and standing 

 on the latter septum. The cameras are thus completely shut off 

 from the siphuncular space. There is, however, no separate siphun- 

 cular wall present in this part, the septal necks forming the only par- 

 titions. The proportional length of this part to the total length of 

 the conch I have not ascertained; it is, however, certain that this 

 open siphuncle extended for the distance of several inches apicad 

 from the living chamber. 



Under the second part of the siphuncle we comprise >that por- 

 tion in which the organic deposits characteristic of Cameroceras 

 and consisting of endocones begin to form. The space included 

 by the last formed endocone is a cone with elliptic or more 

 frequently subtriangular section, the base b^ing parallel to the 

 flat side of the siphuncle [see pl.8, fig.7]. The more convex 

 side is provided with low annulations which are slightly convex 

 forward. The cone is always filled with matrix, like the living 

 chamber and open part of the siphuncle and is what Dewitz and 

 other authors have termed the " Spiess " (or dart) of the endocera- 

 tites. The last endocone is in sections [see pl.9, fig.2] distinctly 

 set off by its darker color from the coarsely crystalline white calcite 

 infilling of the more apical portions of the siphuncle, which suggests 

 that, when left behind by the advancing animal, it contained con- 

 siderably more organic matter than is found in the solid part of the 

 siphuncle where calcite infiltration has taken place. This endocone 

 connects with a cylindric layer of equally carbonaceous lime car- 

 bonate, which being directly adjacent to the septal necks, lines the 

 entire siphuncle and extends forward into the first part to an extent 

 at present not known to me, but certainly not comprising the 

 entire first part, for its absence in the siphuncle for several inches 

 from the base of the living chamber could be ascertained in 



iWe prefer the older term " septal neck " to the later " funnel " pro- 

 posed by Hyatt for the reason pointed out by Foord [1888, p. 130] that 

 under funnel another organ of the recent Cephalopoda is understood. 



