39 i Dr. r. A. Bather on British Fossil Cnnoids : 



{cf. d'Arcliiac's fig. 18), but faint in others, generally those 

 with tendency to stellation {cf. d'Archiac's fig. 16 a), and 

 absent in yet others, especially the more ridged and lobate 

 {cf. d'Archiac's fig. 17a). 



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- 

 zvgal {cf. d'Archiac's figs. 16 a, \7 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 in a 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 lies 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 centits 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). AYhen 

 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, and the ends of the 

 . ridge lie within the triangle (E 21976). The fulcral ridge 

 generally widens to surround the axial canal, and from here 

 it generally tapers towards its ends ; it never widens or 

 thiclvens 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 Avith this and never really forms a straight line. 



