Echinoid Radiolas, Anaulocidaris. 
163 
m) Actual length.7*6 
_ Greatest width.11 '0 
m Thickness across ridge (x — y ). . 2*0 
Thickness of blade over all . . 1'9 
Text-fig. 53. Thickness in median line . . . T2 
Annulus not preserved. 
Numbered «D. 57». St. Cassian. zone of Trachyceras Aon. The small size 
and the shape show that this is almost in the paletiform stage. 
(BW) In the British Museum. 
f) Length c —/.8'5 
Width a—b .13'0 
Thickness along x — y .... 2*0 
a , t x. ,tr Distance d — f .4*25 
jCvf '""V ‘ Thickness over all at d . . . 2*3 
l s A J?.L _ e Thickness in median line at d . 1*8 
' Thickness at e .3'5 
Text-fig. 54. Width of collerette.3T 
Thickness of collerette . . . . 1‘8 
Annulus broken off. 
Registered E 9353. St. Cassian, Klipstkin Collection. 
g) Length c —/.6*9 
Width a—b .11-6 
j. Thickness along x — y . . . . L3 
d e Distance d — f .3'45 
_ f Thickness over all at d . . . . 1‘7 
y Thickness in median line at d . 1‘5 
Text-fig. 55. Width of annulus . 2*1 
Thickness of annulus .... 1*9 
Registered E 9354. St. Cassian, Klipstein Collection. 
h) Length c—f .. . .11*0 
j., t Width a — b .20*0 
c Thickness along x — y . . 1*6 
\/y% \~'d Dist ance &—f .5*5 
: % f Thickness over all at d . . . . 2*1 
■y ~ Thickness in median line at d . 1*6 
Text-fig. 56. Width of annulus . . . . ^ . 3*2 
Thickness of annulus .... 2*5 
Registered E 9355. St. Cassian, Klipstein Collection. 
It is in the Radioli trulliformes that the distinctness of the two species is 
most manifest. 
As usual A. Buchi attains a greater size. In it the ratio of width to length 
has only once been found as high as 181:100, namely in whereas in 
u» 
