154 = Triassic Echinoderms of Bakony. 
Peas 2: 3) 
i rs m 0 
Length of blade in median line 8°5 64 59 tr 
Greatest width of blade . . 10°6 97 S1 9°2 
WenetinroneiN-) Sida amen aO a8 6:0 65 
ISG OSS BE 4 co Bh Y 3) 33 1°25 
Thickness at the centre of 
themblade tans ttre es Oue O75 1:0 tA 
Greatest thickness along the 
IME TTY es oe oe ne 10) 1-0 Os 1°15 
Widthvat annulus en)... 2a 18 ? 1°9 
Thickness at annulus. . . 16 16 ? 1‘85 
Text-fig. 26. Ly () a 
P g Yr u v 
Length of blade in median line 6°6 60 62 62 68 
Greatest width of blade . . 7°6 6'3 O7 64 V3 
Reneth of IN sides a3 5. 2473 3°5 46 36 50 
Kengihp oles asides ake meno O O O 0 
Thickness at the centre of 
thesblade ys 200209 bar 51g) 1:0 1:0 O's O-9 
In these five the annulus is not preserved well enough for measurement. With 
the elimination of the S. side the measurement x—¥y can no longer be given. 
Of the 23 specimens, 15 have G sides, 7 have 5 sides, and one is just on 
the turn. The six-sided blades broadly resemble the trulliformes, but show an 
approach to the five-sided outline. They present the following combination of char- 
acters: the S. side is shorter than the N. side; the handle is removed from the margin 
of the blade, and is set either at right angles to the blade or so nearly at right 
angles that it cannot be seen from above when the radiole is laid on a horizontal 
plane with the outer face uppermost; thus the handle does not enter into the 
measurement of the greatest length of the radiole, as it does in the trulliformes, 
and the distance from the acetabulum to the distal margin is actually less than the 
length of the blade. 
The change from the six-sided to the five-sided outline is due to the shortening 
and final disappearance of the S. side. The handle, which gradually moves nearer 
the centre, thus comes to lie about the middle of the line joining the SW. and SE. 
angles. It is not easy to orient all the five-sided blades, but in most cases the N., 
NE., and NW. sides are still distinguished by the bevel on the inner face, while 
there are still traces of the bevel on the outer surface of the SW. and SE. sides. 
The handle and base afford little help in orienting, since the handle becomes more 
concentrated and therefore more cylindrical, while the base, perhaps owing to the 
greater relative length and slenderness of the handle, is frequently broken off. 
