STRUCTURE OF FOSSIL PENS. 309 
Paley has beautifully, and with his usual 
felicity, described the Unity and Universality of 
Providential care, as extending from the con- 
struction of a ring of two hundred thousand 
miles diameter, to surround the body of Saturn, 
and be suspended, like a magnificent arch, above 
the heads of his inhabitants, to the concerting 
A.) analogous to those of a common feather. These fila- 
ments terminate inwards on a straight line, or base, where they 
usually form an acute angle with the outer edges of the mar- 
ginal bands. Secondly, two marginal bands, B. B., dividing the 
base of the filaments from the body of the shaft; the surface oC 
these bands, B., usually exhibits angular lines of growth in the 
smaller fossil pens (PI. 28, Fig. 6, and PI. 29, Fig. 2,) which 
become obtuse and vanish into broad curves, in larger specimens, 
PI. 29, Fig. 1, and PI. 30. Thirdly, the broad shaft, which forms 
the middle of the pen, is divided longitudinally into two equal 
parts by a straight line, or axis, C. : it is made up of a number 
of thin plates, of a horn-like substance, laid on each other, like 
thin sheets of paper in pasteboard ; these thin plates are composed 
alternately, of longitudinal, and transverse fibres ; the former 
(PI. 28, Fig. 7, f. f.) straight, and nearly parallel to the axis 
of the shaft, the latter (PI. 28, Fig. 7, e. e.) crossing the shaft 
transversely in a succession of symmetrical and undulating curves. 
These transverse fibres do not interlace the others, as the woof 
interlaces the weaver's warp, but are simply laid over, and adher- 
ing to them, as in the alternate laminae of paper made from slices 
of papyrus ; the strength of such paper much exceeds that made 
from flax or cotton, in which the fibres are disposed irregularly 
in all directions. The fibres of both kinds are also collected at 
intervals into fluted fasciculi, PI. 30, f, and e, forming a suc- 
cession of grooves and ridges fitted one into another, whereby 
the entire surface of each plate is locked into the surface of the 
adjacent plate, in a manner admirably calculated to combine 
elasticity with strength. 
