394 Dr. F. A. Bather on British Fossil Crinoids : 
(cf. d’Archiac’s fig. 18), but faint in others, generally those 
with tendency to stellation (¢f. d’Archiac’s fig. 16a), and 
absent in yet others, especially the more ridged and lobate 
(cf. d’Archiac’s fig. 17 a). 
The Cirrus-facets (Figs. 2, 3) lie on the extreme lower 
margin of the epizygal, causing it to project beyond the 
general level of the syzygial face and to cut into the hypo- 
zygal (cf. d’Archiac’s figs. 16 4,17 a). The facet is directed 
obliquely downward, so that the ensuing cirrals are at once 
received into a depression of the hypozygal (Fig. 4). The 
same arrangement obtains, but to a less extent, in the recent 
Isocrinus decorus. The epizygal projects gradually from its 
upper margin down to the facet, so that in a nodal with 
two facets the diameter measured across the facets is greater 
than that at right angles to it. Thus the facet may project 
for more than half its vertical (sc. radial) diameter beyond 
the margin of the hypozygal -(E 21984), but there are con- 
siderable differences in the extent of the projection. 
The outer margin of the facet is a semi-ellipse, but the 
inner margin consists of two straight lines meeting on the 
radius ina rounded angle. This angular boundary is cor- 
related with the radial elevation of the epizygal joint-face 
already described. ‘The fulcral ridge separates the semi- 
elliptical part of the facet from the triangular part, the 
former part being the larger. The ridge approximately 
continues the regular outline of the periphery of the 
columnal ; thus in E 21990, viewed perpendicularly to the 
facet, the ridge les in a straight line with its ends at the 
angles where the straight boundaries cut the curved 
boundary of the facet, and the axial canal lies in the middle 
of the fulcral ridge a little on its inner side. But in most 
cases, the fulcral ridge, in similar view, is bent, the axial 
canal lying nearer to the centre of the columnal, and the 
two halves of the ridge being directed outwards so that their 
ends are in the elliptical half of the facet (E 22027). When 
the angular boundary cuts far into the joint-face, and the 
semi-ellipse is correspondingly reduced, then the axial canal 
and fulcral ridge are carried inwards, aid the ends of the 
ridge lie within the triangle (HE 21976). The fulcral ridge 
generally widens to surround the axial canal, and from here 
it generally tapers towards its ends; it never widens or 
thickens at the ends. The floor of the whole facet is bent 
into a concavity varying in depth and angularity with the 
curve of the outer boundary. ‘The fulcral ridge therefore is 
bent with this and never really forms a straight line. 
