REPORT OF THE STATE PALEONTOLOGIST I903 3O3 



tion the real siphuncle. As Foord [1888, p. 132] has pointed 

 out '' exception might perhaps be taken to this term on the 

 ground that it seems to imply the existence of two siphuncles, 

 an inner and an outer one." Since, however, it will be found 

 convenient to distinguish the fleshy siphuncle from the shelly 

 wall that separates it from the septal chamber, and the term 

 siphuncle has always been used in the latter sense in relation 

 to fossils, he considers the employment of the additional term 

 justifiable. To avoid its illogical and confusing use Holm has 

 proposed a series of terms which it seems practicable to adopt 

 here. These are " ectosipho " for the outer siphuncular tube — 

 ** sipho " being retained for the entire organ — '' endosipho '* for 

 the contents of the ectosipho as a whole ;^ also for the parts of 

 the endosipho are proposed new expressions. He terms 

 " endosiphocylinder " the wider portion of the siphuncle, which 

 is entirely occupied by the more cylindric anterior part of the 

 fleshy siphuncle. This passes posteriorly into the " endosipho- 

 cone " (its walls are Hyatt's '* endocones ") ; from this again 

 proceeds the narrow canal which was termed first " endosiphon " and 

 later " endosiphuncle " by Hyatt and for which is proposed the word 

 " endosiphotube " by Holm [see text fig. 18]. We have, in accord- 

 ance with this terminology, proposed above the term " endosipholin- 

 ing " for the inner, thick, continuous layer of the siphuncular wall, 

 which, according to Hyatt [1884, p.266], is characteristic of Camero- 

 ceras (Sannionites) in distinction from Vaginoceras and Endoceras. 

 This layer is shown in plate 6, figure 3 and text figure 15 {esc) 

 and the sections on plate 7. To the endosiphuncular formation belong 

 further thin, calcified membranes which connect the endosiphotubes 

 and endosiphocones with the ectosiphuncle, and a broad conchio- 

 linous double blade, extending backward from the endosiphocone. 

 The latter structure was originally termed by Holm, who was 



1 Following Hyatt in making a strict distinction between the fleshy 

 " siphon " and its calcareous covers, the " siphuncle," we will employ 

 here the terms " estosiphuncle " and "endosiphuncle." This usage will 

 not vitiate the terms "endosiphocylinder" etc. in which only the radicle 

 of the word siphon is incorporated ; nor will it cause confusion since for the 

 organ termed " endosiphuncle " by Hyatt, a new term is proposed. 



