Echinoid Kadioles, Anaul ocidaris. 
165 
it is broader and less distinct than in that species; it also differs in becoming wider 
instead of narrower towards the median line, a feature which may, however, have 
varied with the shape of the adapically adjacent blade. 
In the absence of distinct SW. and SE. sides, there are of course no distinct 
SW. and SE. bevels. 
Next, as to the form of the inner face. The distinctive ridges of A. Buchi 
have already been described. These ridges are emphasized by the meeting of the 
bevels along the N., NW., and NE. sides. The bevels, however, are not so sharply 
cut as in A. testudo, and are not be detected in all specimens. ln A. Buchi the 
handle and base appear to be rather longer and less flattened than in A. testudo, 
and the acetabulum is less bent southwards; but for a fair comparison a larger 
series of A. Buchi is needed. 
Lastly, as to Ornament. That of A. Buchi is described by Benecke as con- 
sisting of «feinen, radial auslaufenden Streifen» on the inner face, whereas «die 
andere Fläche ist glatt». Better preserved specimens than those accessible to Pro¬ 
fessor Benecke show that the outer face also may be striated, just as is the case in 
A. testudo. The direction is also the same, with a certain modification due to 
different outline. 
The inner face of BM, h, clearly shows radiating striae, of which those pass- 
ing towards the distal margin have a curious, wavy course. The striae that meet 
the long curved Southern margin (= SW., S., and SE., of A. testudo) pass over 
it as in Ä. testudo (Text-fig. 18, Inner face); but then instead of those to the SW. 
and SE. Crossing the others (Text-fig. 18, Outer face) they continue their radiation 
towards the distal margins. Their course is, in fact, more like that in the spatuli- 
form radioles. This, no doubt, is why there is no trace of concentric ridging. ln 
many cases, however, the continuation of the striae on the outer face cannot be 
detected; instead, the surface is merely punctate, or sometimes slightly granulär, 
with no definite arrangement of the markings. Such surfaces are probably those 
which Professor Benecke describes as «glatt». 
This comparison of the trulliform radioles not only brings out most clearly 
the distinctness of the two species, but also shows that A. testudo is more special- 
ised than A. Buchi. The chief evidences of specialisation are the greater relative 
width, the more angular and more definite outline, the more clearly cut bevels, and 
the curious Crossing of the striae on the outer face. 
4. R a d i o 1 i paletiformes. 
(Pl. X, figs. 253—255.) 
The specimens examined are the following: 
(MM) In the Palaeontological Museum, Munich. 
h) 
Greatest length.6'8 
Greatest width.10'7 
Thickness of blade along line x — y . P2 
6-8 
107 
Thickness of blade along line d . . . 17 
Thickness in median line at same level l',5 
Width of collerette (annulus broken) . 2'0 
< cxt-tig. 57. 
