Echinoid Radioles, Cidaris parastadifera, __ 209 
The average diameter given by ScHAFHAuTL is 2 mm. (i. e. 0°23 of length). 
The mean of the extremes presented by the Bakony radioles is 0°21; but this is cer- 
tainly below the average, for the very thin shafts are rare in comparison with the 
very thick ones. 
The ornament varies no less than the shape, so that, were it not for the 
complete series of gradations, many of these specimens would scarcely have been 
referred to the same species as the two varieties of form hitherto described. Those 
two varieties are also found in the Bakony material. The longer form of the holotype 
is said by ScuarHdutL to have at most 9 longitudinal ridges, of which 4 are visible 
from any one side; these ridges meet distally in a very low, somewhat conical point ; 
each ridge is beset with a row of usually 9 pustules one above the other, with 
a distal rake, elliptical, swelling towards their ends, usually in horizontal rows, but 
also often alternating; between each ridge is a narrow linear space. This description 
implies a subcylindrical shaft with ridges evenly distributed, and such do actually 
occur. It is, however, doubtful whether the radioles in the holotype are of this 
nature; they lie on the matrix, so that only one face — the adapical — is seen, 
and the wording of the description is quite consistent with the more probable view 
that the shafts are compressed and the ornament not evenly distributed. 
By far the greater number of the shafts from Bakony show some sign of 
dorso-ventral compression. When this is well marked the pustules on the lateral 
ridges are the most prominent and produce a serrate edge (figs. 381, 385)); the 
supposed adapical face is the more rounded (fig. 383), and bears more prominent 
ridges and pustules than does the adoral face; this latter is relatively flattened and 
usually bears finer and more closely set ridges with less pronounced pustules. In thin, 
elongate radioles, the adoral face is often quite smooth (fig. 388); in more lanceolate 
radioles, that face may be smooth in its proximal half, becoming ridged distally ; in 
the more swollen, subclaviform radioles, its ornament is better developed and differs 
but little from that of the adapical face (figs. 376, 377). 
The smallest number of ridges observed is 3, namely two lateral and one. in 
the middle of the adapical face, the adoral face being quite smooth. ‘The long 
radiole from Cutting IV has 4 ridges on the adapical face. Compressed lanceolate 
forms may have as many as 6 ridges on the adapical face, accompanied by 6 to 5 
on the adoral face. A rather more claviform shaft from Jeruzsalemhegy has 7 or 
perhaps 8 adapical ridges, and 5 adoral with a trace of a sixth. The regular sub- 
claviform shafts have about 12 ridges as a rule, but two of this shape from Jeru- 
zsalemhegy have as many as 16. 
The short swollen radioles, referred by ScuarHAutL to C. marginata are no 
doubt short examples of the subclaviform type, and it is consistent with this that 
they were said to have 10—12 ribs. Scuarnaurt’s figures, however, cannot be said 
to indicate more than 6—S8 ribsin all. The smallest complete subclaviform radiole in the 
Bakony material is from Jeruzsalemhegy: 53 mm long, greatest diameter 1 6 mm., 
number of ribs 10. This specimen does not agree with ScuarnAurt’s statement that 
the handle is one-third the length of the radiole, since it is only O°8 mm. long; 
but then the statement is equally inapplicable to the specimen shown in ScHarHauTL’s 
figure 2a. Although then the Bakony material yields no specimen precisely agreeing 
with Scnarnauti’s description of this form, still it contains several radioles near 
Resultate der wissenschaftl. Erforschung des Balatonsees. 1. Bd 1. T. Pal. Anh. 14 
