Echinoid Radioles , Amiulocidaris. 
161 
(BM) In the British Museum. 
_27 0 
from 
acetabulum 
J_18*0 
i 
» 
2‘2 thick over all, 
1‘4 thick in median line 
L. 9-0 
» 
» 
3‘3 » » » 
2-4 » » 
- 4M 
» 
» 
2 - 5 » » » 
. -restored acetabulum 
Text-fig. 48. 
Registered E 9351. From St. Cassian, Klipstein Collection. 
Slightly crushed at proximal end; annulus unknovvn. 
e) 
/ __I\. 18‘0 from acetabulum.1‘4 thick at point 
V 9'0 > » 2‘3 thick over all, 1'8 thick in median line 
1 ’9 » » 3’0 » at annulus; vvidth 4’ 1 
-acetabulum. Height of collerette from annulus 1‘4 to l - 6. 
Text-fig. 49. 
Registered E 9352. From St. Cassian, Klipstein' Collection. These two radioles 
are scarcely removed from remiform. There are also in the Klipstein Collection 
three radioles, more definitely spatuliform, labelled Cidaris Buchi by Klipstein 
(regd. 36524). 
Comparison of the Cassian radioli spatuliformes vvith those from Bakony, 
shows that, although there are a few quite small specimens, still most of those 
collected are much larger. No radiole from Bakony exceeds 18 - 3 mm. in length. 
MM, d, RAW, b, c, HMW, d, e, h, BM, d, e, vvere all well over 20 mm. long, and 
BM, d was probably not the only one that attained 27 mm. Therefore, as with 
the remiformes, the length of the Cassian spatuliformes to that of the Bakony 
specimens is 3:2. The ratio of thickness to length is about the same in the two 
species. The essential difference lies in the median excavation, giving rise to lateral 
ridges, in A. Buchi. The extent of this can be gathered by comparing the thickness 
of the blade over all with the thickness in the median line. Thus in BM, d, at 
9 mm. from the acetabulum the median excavation is 27’2 per cent of the total 
thickness at that level; at 18 mm. the excavation has increased to 36 3 per cent. 
In this specimen the concavity is particularly evident. In the other specimens the 
maximum excavation is 26‘6 per cent (in HMW, g), and the minimum is 12‘5 per 
cent (in HMW, d). It will be observed that the excavation is quite as obvious in 
small radioles as in large ones. The ridges are manifest on the inner face, and the 
excavation of the outer face is very slight or nonexistent. We have already seen 
that many spatuliform radioles of A. testudo have no such concavity, and that, when 
present, it rarely cxceeds 12*5 per cent; only in Jeruzsälemhegy g does it amount 
to as much as 25 per cent, and this is quite exceptional. 
Resultate der Wissenschaft!. Erforschung des ßaiatonsees. I. Bd. 1. T. Pal. Anh. 11 
