4 The American Geoloifist. July, 1895 
The tubular sliejith (fig. l,pl. I.) extends apicad of the bro- 
ken end to a length of 7 mm. without change of diameter, but 
bends slightly and is truncated or bevelled at the apical end 
forming an acute angle in the section on the ventral or 
straiglit side and an obtuse angle on the dorsal or gibbous 
side of the siphon. The whole length of the section is 31 mm., 
the greatest transverse diameter is 9.5 mm., and the diameter 
of the broken end is 7.5 mm. Apicad of this sheath the fill- 
ing was not dense as in the original of figure 8 of Clarke, or 
figures 3-6 given in this paper, but very loose semicrj^stalline 
calcite, and in the middle of the broadest part the entire cen- 
ter was hollow with an intruded piece of the darker colored 
matrix on one (the dorsal) side. T^lis local absence of de- 
posits can be accounted for because the upper right hand side 
of the specimen removed in making the section, was crushed 
opposite this cavity. This wound may have been made dur- 
ing the life of the animal and, if so, this would account for 
the absence of deposits in the center as well as the loose sub- 
crystalline aspect of the filling above. The character of the 
deposits and the differences between those of the periphery 
and central parts is given accuratel}^ in the figure. The dark 
mass on the left upper corner above the hollow space is the 
intrusive matrix alluded to above. This space was completel}^ 
inclosed so that the matrix did not penetrate into its interior. 
The pseudocrj'stals surrounding it were distinctl}^ visible 
through the hole in the wall of the siphon before the right 
side was cutaway in nuiking the section. The wound in the 
right side had been parti}' closed by these internal deposits 
as the animal grew in length but these repairs did not fill it 
out to the surface of the siphon, they merely shut ofi' the en- 
trance to the ventral parts of the hollow. 
The peripheral de^^osits are radiatory in arrangement and 
evidently organic. These deposits are penetrated at the tip 
by the endosiphon which is a tube open at the end. The wall 
on the dorsal side is a distinct dark line showing that it was 
composed of conchiolin. The limits on tlie opposite side are 
less definite but perfectly perceptible. The center near the 
lower end is completely filled with the red matrix, identical 
in aspect with the piece of matrix on the left of the hollow 
above and that filling the interior of the truncated sheath. 
