2 The Ainerican Geologist. Jaly, 1895 
I have been able to find the endoeones of his figure 8, al- 
thougli there are only slight indications of their presence in 
this specimen, and the deposits are much more solid in this 
specimen than in anj^ EmJoceras I ever saw. Thej^ greatly 
resemble in color and general aspect those of Xarlhecoceras, 
mentioned below, and maj' have been built in the same way, 
namely, by the sheath while shrinking towards the central 
axis. This specimen is important because it shows clearly 
the alteration in shape of the sheath and that it has shrunk 
in size. There are no indications that it built any deposits 
while it was being withdrawn upwards except in a small 
patch on one side. Here the radiatory lines are inclined as if 
there had been a steady withdrawal upwards or orad at 
the same time that there was a shrinkage in bulk towards the 
central axis. The shape of this sheath explains the truncated 
end of that given in this paper, figure 1, and shows that the 
bevelled apical end of this and its acutely angular ventral 
point is really the normal form derived from this younger 
stage of the sheath. It shows also that this tube is not a true 
endosiphon. although it so closely resembles one, but is in 
reality the termination of a retreating sheath. 
I have not been able to find satisfactorj' evidence of the 
general existence q[ Jibrous radial structure. Obscure radia- 
tions occur but close study of these show that the radial lines 
are the apparent boundaries of pseudocrystals, not true fibres. 
They may be attributed to the mode of deposition of the cal- 
careous matter, but can hardlj' be considered integral struc- 
tures of the solid filling, which, in my opinion, is an amorphous 
pseudocrystalline deposit often denser than in Endoceras 
but only secondaril}^ radiatorj'^ in structure. I do not wish 
to be understood as stating that the structure of the filling is 
not radiatory. On the contrary there is a decided radiation 
in the pseudocrj'stals that shows well on broken and abraded 
surfaces, but I differ somewhat from Prof . Clarke in my inter- 
pretation of the meaning of these lines. When radiating lines 
are present as integral structures the fibrous nature of the de- 
posits are easily demonstrated. Such structures occur in the 
siphon of Xarthecoceras* a new genus of Endoceratidtv 
*Siiice writ infj the above. J have consulted one of my drawings and 
the fine specimen from -whicli it was taken and find distinct but sjio- 
