.314 NEW YORK STATE MUSEUM 



middle parts of the " Blatt." The former are described as being 

 a: continuation of the two winglike lamellae that flank the en- 

 dosiphosheath and the latter, which is characterized by its sculp- 

 ture, as a continuation of the middle part of this endosiphosheath. 

 This difference is in our material, if anything, still more apparent, 

 and the two parts are entirely separated owing to their different 

 places of origin. The wings are formed on the outside of the 

 endosiphocone, while the middle part, which is the real tube of 

 the endosiphocoleon, is formed within the endosiphocone [see 

 text fig. 14] . The two conchiolinous bodies are hence in Camero- 

 ceras brainerdi separated by a layer of gray organic lime 

 carbonate, the endosiphosheath [see pl.9, fig.i and text fig. 14]. It 

 is, however, apparent that in V. belemnitiforme both 

 parts are considered as having originated on the outside of the 

 endosiphocone or to be the direct continuations of the endosipho- 

 sheath, and the figure [see text fig.4] would seem to bear out this 

 conclusion. 



Germane to this observation of Holm as to the origin of the 

 middle part of the endosiphocoleon is the further observation 

 and resultant conclusion which is cited here [/. c, p. 15, transla- 

 tion] : '' With the exception of the conchiolinous calcareous 

 sheath covering the endosiphocone itself, there occur no traces 

 of such sheaths secreted by the siphon, within the siphuncular 

 tube. Neither does the calcareous filling show any conical sur- 

 faces of separation. Since, moreover, the lamellae of the sword- 

 like structure which proceeds from the endosiphocone form a 

 direct, uninterrupted continuation of the sheath of the siphon it 

 must be assumed that the siphon did not secrete the conchio- 

 linous calcareous sheath until the animal was full grown and no 

 longer enlarged its conch nor advanced in the siphuncular tube." 

 This blade in V. belemnitiforme is supposed to have 

 reached to the apical end of the siphuncle. 



Our observations would indicate somewhat different relations 

 in C. brainerdi. First the presence in transverse sections 

 of a series of embracing crescentic conchiolinous sheaths [see 

 pl.7, fig. I and text fig.8], which are the remains of the winglike 



