EXPLANATIONS OF PLATE IX. 
GrapToLitaus Logani, page 100. 
Fig. 1. A specimen of slate, preserving portions of three individuals (two only given 
“ 
a“ 
in the illustration). The disc had probably been removed by maceration 
before they were imbedded, but the stipes are preserved to a length of 
more than seven inches. It does not appear that this exhibits the entire 
skeleton : the stipes were originally longer. The serrated margins are not 
always shown at equal distances from the centre; but this is due to acci- 
dental position, some stipes showing the exterior surface for some distance, 
and then gradually turning and becoming flattened laterally. 
. A specimen showing the disc almost entire. 
. An individual showing the exterior surface the central portions entire, with the 
impression of the connecting disc, some portions of which remain attached 
to the stipes. The extent and outline of the disc are distinctly seen. 
The appearance of serratures is due to exfoliation, which shows the impres- 
sion of the celluliferous side of the stipe upon the stone. 
. A specimen exhibiting the half of an individual, with the disc unequally ex- 
tended between the rays. The margins are all apparently entire, and this 
inequality, to whatever accident due, existed in the living animal. 
. Exterior view of an individual showing some remaining portions of the disc; the 
stipes are all broken off beyond the bifurcations. 
- Another individual showing the inner side, with the commencement of the cells, 
which appear in some places in double series. The substance of the dise 
is removed. 
. Enlargement of the exterior surface of the central portion of the specimen fig. 5. 
. Enlargement of the inner surface of the specimen fig. 6, giving the appearance 
of a double series of cells separated by a depressed line in the substance of 
the stipe. Sometimes this separation appears to be actual, while else- 
where the apparent division is due to the depression along the centre. 
. Enlargement of a fragment of a stipe, showing the form and proportions of 
the cellules. 
