234 



STRUCTURE OF FOSSIL PENS. 



Hence it is clear that the same causes which produced 

 these effects during the deposition of the Lias at Lyme 

 Regis, produced similar and nearly contemporaneous effects, 

 in that part of Germany which presents such identity in the 

 character and circumstances of these delicate organic re- 

 mains.* 



Paley has beautifully, and with his usual felicity, de- 



that which he has designated by the name of Loligo Aalencis ; but I have 

 yet seen no structure in English specimens like that of his Loligo Bol- 

 lensis. 



* Although the resemblance between the pens of the Loligo and a fea- 

 ther (as might be expected from the very different uses to which they are 

 applied) does not extend to their internal structure, we may still, for con- 

 venience of description, consider them as composed of the three follow- 

 jng parts, which, in all our figures, will be designated by the same letters, 

 A. B. C. First, the external filaments of the plume, (PI. 28, 29, 30, A.) 

 analogous to those of a common feather. These filaments terminate in- 

 wards on a straight line, or base, where they usually form an acute angle 

 with the outer edges of the marginal bands. Secondly, two marginal 

 bands, B. B., dividing the base of tiic filam.ents from the body of the shaft' 

 the surface of these bands, B., usually exhibits angular lines of growth in 

 the smaller fossil pens (PI. 28, Fig. 6, and Fl. 29, Fig. 2,) which become 

 obtuse and vanish into broad cur.ves, in larger specimens, PI. 29, Fig. I, 

 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 slieets 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 (P!. 28, Fig. 7, e. e.) crossing the shaft trans- 

 versely in a succession of synmielrical 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 adhering 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 tiic 

 fibres are disposed irregularly in all directions. The fibres of both kinds 

 are also collected at intervals into fluted fisciculi, PI. 30, f, and c, form- 

 ing a succession of grooves and ridges fitted one into another, whereby 

 the entire surface of each plate is locked into the surface of the adja- 

 cent plate, in a manner admirably calculated to combine elasticity with 

 strength. 



