). - 



REPORT OF THE STATE PALEONTOLOGIST I9O3 3OI 



2 Former observations on endosiphonal structures and the termin- 

 ology of the latter 



The endosiphuncular structures of Cameroceras brain- 

 e r d i which concern us most here are the flattened tube extend- 

 ing backward from the " Spiess," the fine, often capillary tube 

 extending the greater length of the siphuncle and certain thin 

 longitudinal layers of dark organic limestone radiating from these 

 tubes to the walls of the siphuncle. 



The attention of paleontologists was directed to similar 

 structures only a comparatively short time ago, though the fine 

 threadlike endosiphuncle had already been noticed by Barrande 

 in a Newfoundland species (Orthoceras insulare) 

 [see 1867, v.II, t.430, fig.5, 8-1 1 ; t43i, 

 fig.8-io] and also been described by Dewitz 

 [1879, p. 1 72, 173, fide Holm] and Schroder .'^'. 



[1881, p.76, t.2, fig.8d]. Dewitz also men- ■ \^^'' 



tions [1880, p.377] that ''in some species 

 membranes seem to have proceeded from 

 the posterior end of the fleshy siphuncle, 



,. 1 - ^ 1 ^ r 1- . Fig. a "Endoceras com- 



which often, at least lor some distance, mune." section of siphuncle. 



s, siphuncular side ; a s, anti- 



extended to the internal wall of the siphuncular side. (Copy from 



Dewitz) 



siphuncular tube, and which also secreted 



covering sheaths, in which organic carbonate of lime was deposited," 

 and adds, " These membranes probably served to attach the posterior 

 end of the fleshy siphuncle to the interior wall of the siphuncular 

 tube." He also figures a transverse section of Endoceras 

 commune [pi. 17, fig.7] which shows three longitudinal mem- 

 branes radiating from the endosiphuncle, but which do not reach 

 the siphuncular wall [see text fig.2]. 



The flattened tube extending from the '' Spiess " appears to 

 have been first noticed by Dawson in a species of Piloceras 

 [1883, P4]- Sir William states [p. 3] that "the lower part of 

 the shell is divided by a vertical partition crossing its longer 

 diameter," and again [p.4] that the internal cone '' is flatter 

 than the siphuncle, ending at the apex in an edge which is 

 attached to a central shelly plate crossing the lower part of the 



jb 



