Diadematoid Radioles. ; 229 
distal end of the fragment they are 16 or a little more to 1 mm. They are therefore 
both coarser and more distinct than in C. linearis. The broken end of the radiole 
is not easily seen, but it is plain that the ridges are the outer edges of stout wedge- 
shaped radiate septa. A dark iron-stained spot in the centre of the broken end, 
suggests the former presence of a relatively narrow lumen. ‘The base is rather 
massive and elongate, with rounded smooth annulus, no sign of a collerette, wide 
acetabulum with raised, obscurely crenelate margin. Total length of fragment 
2°5 mm. Diameter at annulus 0°62 mm. Wourmann describes the shaft as «oben 
und unten von gleicher Starke», but draws it as thinner in the middle region; 
really it tapers from the annulus towards the broken end. 
To this species W6xHRMANN provisionally referred some interambulacrals found 
in the same rock. His figure (pl. v, f. 17), which shows two of them, did not 
lead me to suppose that they belonged to any species found in Bakony, but 
examination of the original specimen now proves it to belong to the form already 
described (p. 118) as Mesodiadema latum. The fragment (PI. XIII, fig. 419) comprises 
five interambulacrals in association, and shows the great transverse width of the 
plates and the characteristic curve of their upper and lower margins, features by no 
means obvious in WourMann’s figure. 
The radiole on which Cidaris Schwageri was founded is no doubt that of a 
Diadematoid, and it may have belonged to Mesodiadema latum. ere that proved, 
the latter species would be called Mesodiadema Schwageri. But the supposition is 
not proved, and the fact that the radiole C. Schwageri has not been found in those 
Bakony localities that have yielded Mesodiadema latum goes far to discredit it. 
Turning to the Bakony material, it is rather strange to find no representative 
of C. flexuosa; on the other hand, radioles superficially resembling C. linearis, 
and in a less degree C. Schwageri, are abundant. 
Setting aside a possible radiole of C. Meyeri, one can divide the rest into two 
groups according to size. Size of itself is not generally regarded as differentiating 
species; but when the specimens all occur in the same localities and beds, and 
when there is a notable absence of sizes intermediate between the large and the 
small, it is impossible to ascribe the difference to age, to environment, or to nutrition, 
or indeed to anything except specific or varietal character, It is also noteworthy 
that, although the larger radioles may be compressed, still the distinctly bicarinate 
and muricate forms mentioned above appear as developments of the smaller size 
alone; and this militates against the supposition that the smaller radioles are merely 
secondary ones. All these radioles might perhaps be regarded as varieties of C. 
linearis with lesser individual variations; but this would leave out of account the 
microstructure and the size of the longitudinal striae. The lumen also, as will be 
seen from the accompanying table (p. 230) is generally narrower in the Bakony 
radioles than in those of C. linearis of St. Cassian. Therefore, to avoid a row 
of subspecific and varietal names, it is well to give the former a distinct name 
to which varietal names can then be affixed. Grouping all under the new name 
C. lineola, we distinguish var. major and minor, the latter having its bicarinate 
and muricate forms, for which Latin names are not required. 
