Echinoid Radioles , Ciduris Waechteri. 
193 
but it suggests an incipient «Endkrone», such as is common in cireumapical radioles. 
A similar feature occasionally noted is the actual excavation of the distal end, but 
this is also seen in smaller specimens. 
There is, no doubt, considerable difference between some of the large, massive, 
rounded radioles ascribed by Münster, Klipstein, and such old authors to C. catenifera, 
and the smaller, flattened radioles agreeing with the holotype of C. Waechteri. 
The racjioles are rarely complete, but estimates based on the larger fragments in 
the British Museum (36518, 36519) give measurements 66 mm. X 11'4 mm. and 
75 mm. X 16*4 mm. Münster’s reconstituted fragments (f. 23) give 59mm.X 10 mm. 
The figure of the complete holotype of C. Waechteri measures 28'3 mm. X 5‘8 mm. 
A complete radiole labelled C. Waechteri by Klipstein (Brit. Mus., E 4608) measures 
23‘8 mm. X 4'8 mm. Between these extremes of size, however, there is every 
possible gradation. 
There is also a marked contrast between the rounded ends with diameters 
16.4 & 15‘7 mm. and 9'8 & 9'0 mm., such as characterise the larger radioles, and 
the flattened section found in some tvpical C. Waechteri. It may, however, be 
observed that the extreme flattening is due to crushing, and that the dorso-ventral 
compression is less marked at the distal end, which is in fact rounded, as described 
by Wissmann ; thus, an uncrushed shaft (Brit. Mus. 75862) has at the middle of 
its length the diameters 5"3 & 3‘9 mm., and near its distal end 5*5 & 4 5 mm. 
Taking the greater diameter as 100, the ratios of the shorter diameter are, for the 
larger radioles, about 95 and 91, and for the smaller radioles about 81. 
So far then as outward form is concerned, the differentiae of the largest 
radioles seem to be the more cylindrical shaft, the more equal distribution of pustules 
on its two faces, the diminuticn in size and number of the pustules, especially 
near its distal end, and the absence of a serrate margin. The number of radioles 
presenting these extreme characters is relatively few. The holotype of C. Brauni 
itself scarcely shows them. Many radioles presenting all the characters of the 
holotype of C. Waechteri reach the larger size, so that there is a complete series 
of gradations in every respect. 
Acting presumably on some such considerations as those just given in detail, 
Laube and a few others have merged the two forms of Münster and Wissmann in 
a single species, which they have as a rule called Cidaris Brauni. In this, however, 
they have also included Cidaris similis , which, as shown above, is entitled to 
independence. Hesse (1900, p. 230) while eliminating C. similis on the ground of 
its distinct micro-structure, has stated that C. Brauni and C. Waechteri completely 
agree in their micro-structure, and has therefore united them under the name 
C. Brauni. As to the facts I can confirm the observations of Hesse, but must point 
out that the name Cidaris Waechteri Wissmann (1841) is incontestably prior to 
Cidaris Brauni Desor (1846). 
The micro-structure has been studied in cross-sections of two radioles from 
St. Cassian closely agreeing with the original C. catenifera Münst. and C. Waechteri 
Wissm. The illustration (PI. XV, hg. 443) represents the structure of the former; 
but it so closely resembles the structure in the latter that a separate figure seemed 
quite unnecessary. As described by Hesse .(1900, p. 229) the radiate septa have 
lost their straightness, are wide apart, and united by long trabeculae so as to form 
a coarse network, which, though irregulär, is still governed by the radiate structure. 
Resultate der wissenschaftl. Erforschung des Balatonsees. 1. Bd 1. T. Pal. Anh. 
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