Explanation op platf. 28. 
49 
g- • Con vex upper surface of portion of another recent 
P n, of the same kind. The structure of figs. 3 
and 4 closely resembles that of the fossil species 
7pToo -d also 
hov I them, the 
ny plates are composed of a series of longitudinal 
fih*^*^^’ ' another series of transverse 
fibres. The disposition of the transverse fibres is 
mos simpk in the recent species; passing obliquely 
fibtwards from each side of the central shaft! like 
e barbs or fibrils in the vane of a feather, and 
eing most distinct towards the outer margin. 
recen! ^bres are scarcely visible in the 
cent species except where they are collected into 
wth f those parts 
ch correspond with the marginal bands of the 
fossil species. (Original.) 
• of the Pen, ,.i«ed like the shaft of a 
^ quill between its fibrils. 
the f dissected by 
tural T r containing its na- 
J ! '? ' i 't is a black shining 
^ ^ifitery fracture, and 
mbhng the substance and fracture of the fossil 
(Oria-ind not much reduced by desiccation. 
tlmsirf'”'"';! P'" of Wise 
Shaft.’ nv' bands; C. axis of the 
with ’ + 'c j^^^tory duct of the Ink bag, distended 
^^th petrified Ink.* (Original.) 
* In this e 
Ifands. ^ cimen we see distinctly the disposition of the marginal 
