52 Triassic Echinoderms of Bakony. 
Mength fofishortestscrenellay ss mayen eet OEE 
Length oflongestscrenellage., 520 0 .-aneec ner, 
Width. ofaycrenella yy a espe eet 0 eee eee Oe Oec) 
Distance from lumen to apex of radial triangle . . . O7 
Distance from apex to base of radial triangle . . . O15 \ 
Syzygial faces (figs. 108—110, 112): The number of syzygial columnals, as 
already explained, is relatively few; and of these again only a small proportion 
expose the syzygial faces. The stems appear to have broken with equal or even 
greater ease at the joint above the nodal, while there are not a few cases of syzygial 
ossicles united to each other but separate from the rest. These facts suggest that 
the union was firm and not brittle. It is impossible to say whether there was any 
difference in structure between the syzygials still united and those that have 
come apart. 
Epizygals (figs. 109, 110, 112). In most cases the surface is worn, and merely 
suggests a normal joint-face with all its features less accentuated: one can trace 
the peripheral crenellae, the radial ridge-groups, and the depressed petal-floors; the 
radial triangle, however, appears to be absent, or else present only as the end of 
a single radial ridge, formed by. the concrescence of the ridge-group. Better 
preserved specimens show a more complicated structure. There are traces of the 
original crenellae at the outer ends of the petals; but they appear to be overlaid, 
or in part replaced, by another system of crenellae very much finer. These fine 
crenellae surround the petal-floor, always at right angles to its border, and pass 
without break into the adradial series, which form two rows of crenellae alternating 
and inosculating along the radius, to which they are at right angles. Centrally they 
merge into the raised area. Five of these crenellae and five intervening grooves go 
to half a millimetre, i. e. the width of one crenella is 0°05 mm., or one-tenth the 
width of a normal crenella. In these specimens the radial triangle is very faintly 
indicated, and the rebate rim does not pass round the petals. The crenellae there- 
fore come right to the edge of the suture, but their extreme fineness renders them 
imperceptible on the side-face of an unbroken syzygy. 
Hypozygals (fig. 108) in their simplest form show a raised margin to the rosette, 
outside which are the radial triangles and the rebate margin The petal-floors are 
gently swollen. The extent to which the crenellae are atrophied varies much: sometimes 
they are merely obscured; sometimes the radial ridge-groups are represented by slight 
ridges; sometimes the only traces of the original crenellae and granules are bands 
of colour lighter than the petal-floors, owing to the larger proportion of organic 
substance in these latter.* Well-preserved specimens show a new series of fine 
crenellae similar to those of the epizygal and similarly arranged: they bear no 
relation to the degree of atrophy of the larger crenellae, but both may be present 
in the same region. 
The cirrus-facets (figs. 114—116) occupy the whole height of the nodal, while 
indications of their presence may sometimes be detected on the supranodal and 
hypozygal; they are directed very slightly upwards. Each facet is transversely 
elliptical, with a well-defined rim, which however always tends to be deformed from 
* See BaTHER «Crinoidea of Gotland. I.» Svensk. Vet.-Akad. Handl XXV, No. 2. p. 151; 1893. 
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