26 
Triassic Echinoderms of Bakony. 
the internode approaches moniliform (c); a truly moniliform stem can hardly be said to 
occur among Pentacrininae. 
The suture-line is usually flush with the side-face (text-fig. 2 e), but may be 
depressed in a groove (text-fig. 2 f), the upper and lower halves of which respectively 
form a r e b a t e around each joint-face. The depression of the suture is frequently confined 
to the radial regions ; if this be carried far, as is often the case in stellate, substellate, or 
concavistellate columnals, there is developed a transverse ridge at half the height of the 
columnal, and so is produced the scalariform type of internode. A stem may be 
scalariform and stellate in its proximal region, and gradually change to cylindrical in its 
distal region. 
In addition to the changes in external form produced by Variation in size or shape 
of the columnals, there may be Ornament on the side-faces. This consists usually of small 
t u b e r c 1 e s, which may grow together into horizontal or vertical r i d g e s. If such Ornament 
be absent, the side-faces are described as smoot h. 
The joint-faces between ordinary internodals are described as normal and, though 
they may be slightly different in the different regions of the stem, or where they approach 
the nodals, present no marked Variation within a single species. The joint-faces of the syzygy 
are called s y z y g i a 1; they usually differ considerably from the normal, especially in pro- 
Text-figure 2. Internodals of the Pentacrinine Stem. 
portion to their distance from the proximal end of the stem, and that ot the epizygal often 
differs from that of the hypozygal. 
The joint-face is divisible into five similar interradial s e c t o r s‘, each of which is 
bilaterally symmetrical. In the centre of each joint-face is the opening of the axial canal or 
lume n, which may be circular, or pentagonal, or quinquelobate. The angles or lobes, 
when present, do not alternate with the angles of the columnals, but are like them inter¬ 
radial. This Variation from ordinary crinoid structure is probably due to secondary growth 
of stereom, and the Statement seems liable to exceptions. At any rate the axial cords of 
the stem are radial, and the branches from the axial canal to the cirri are inevitably radial, 
so that the lumen of the stem on approaching the node tends to develop radial lobes. So 
little attention has been paid to this point, now known to be of deep significance, that the 
published figures can scarcely be trusted. Thus, even in P. H. Carpenter’s Challenger 
Report (pl. XXXII), we find the lumen of the same syzygy with interradial angles in figure 1, 
and radial angles in figure 2. 
We proceed with the normal joint-face (text-fig. 3). 
Surrounding the lumen may or may not be a distinct central area. This may be 
flush with the general floor of the joint-face, depressed below it, or raised above 
* P. H. Carpenter in some passages (Challenger Rep. Stalked Crinoids, p. 271) has used the 
term «scctor» for the pctaloid figure formed by the crenellac; but such restriction of a familiär term is 
scarcely warranted. 
