182 Triassic Echinoderms of Bakony. 
annulus nor acetabulum shows any marked obliquity. Compared with the massive 
shaft, the acetabulum is small, the annulus slight, and the collerette short: length 
of radiole, 22°3 mm.; greatest diameters, 9°4 and 87 mm.; diameters of annulus 
24 and 2:3 mm.; from base of annulus to top of collerette 12 mm. From the 
point on the adoral face where the sagittal line bends to the apex, a slightly more 
confluent row of pustules passes in a slightly proximal direction on to the adapical 
face, thus tending to form a rim round the distal end. The sagittal line, in passing 
from the rim on the adoral face to the distal extremity, follows a faintly convex 
curve; but on the adapical face the corresponding tract follows a faintly concave 
curve. 
In specimens 1, 0, p, g, 7, the features adumbrated in m are intensified, as 
shown in figures 319—326. The rim round the distal end is more definite and, 
on the adapical side may be produced downwards in a distinct angle (fig. 321). 
Thus, as seen from the distal end (fig. 320), the radiold is almost triangular in 
section. This is the kind of modification that produced the Cassian Cidaris trigona, 
but here it is not carried so far as in that species. 
The radioles nearer the apex of the test seem to be represented by forms 
with less dorso-ventral compression, less marked bilateral symmetry, more regularly 
pyriform, but with the distal end flattened or truncated, almost at right angles to 
the axis, and sometimes hollowed, as in C. alata poculiformis. Specimen s (figs. 
327—329) appears to represent the first incoming of this form; its distal end is 
still slightly rounded, and is strongly spinulose. In ¢ (figs. 330—333), which represents 
the extreme modification in this direction, the rim is almost continuous, and within 
it, roughly parallel to its edge, are rows of pustules, rising a little higher on the 
adoral than on the adapical side; the diameters of the truncate top are 10°4 and 
10 mm.; it is hollowed excentrically towards the adapical margin. 
Relations of the Mutation. — This last form approaches close to that 
regarded as the extreme adapical form of C. alata poculiformis, and it is hard to 
say to which species the specimens represented in figures 306—309 should be 
referred. The resemblance between these most moditied forms does not prove the 
specific identity of C. alata and C. dorsata, for the normal forms of the ambital 
and supra-ambital radioles are readily distinguished. 
A radiole of this last form has been described by Quenstept (1875, p. 194, 
pl. Ixviii, f. 77) as Radiolus dorsatus «ein wahrer fungiformis», and said to come 
from the Cassian beds of St. Cassian. This is the only such form I have ever 
seen or read of in the Cassian beds, where it must certainly be rare, if inded it is 
really found in them. Its occurrence does not affect the distinctness of our Raiblian 
mutation, which is based on other characters. 
