126 Triassic Echinoderms of Bakony. 
is not quite regular; especially is it disturbed by the prominent tubercles already 
mentioned as occurring in the smaller intercalated set. Clearly, certain tubercles of 
the main meridional series are growing at the expense of the others, and are over- 
lapping the sutures between successive ambulacrals, .while the outer portions of the 
ambulacrals remain quite distinct. The overgrowth seems more pronounced in the 
ambital region. This specimen therefore strongly corroborates the views first enun- 
ciated by Lampert (Bull. Soc. Yonne, 1900, p. 8) as to the evolution of majors 
from primaries; but the stage here attained is more primitive than that of the 
Diademopsis serialis which he there figures, inasmuch as one cannot say that 
definite majors here exist at all. 
The width of the perradial tract is 1.3 mm. at the widest place, and the 
diameter of a main tubercle is about 0.6 mm. The height of an ambulacral in the 
same region is 0.8 mm. From the perradial tract the ambulacrum slopes gently at 
first, and then more steeply. The two podial pores are on the gentle inner slope. 
The outer slope becomes much more steep adorally, as described under 77iad- 
ocidaris persimilis. The outer limb of each ambulacral plate is directed adapically 
over the inner slope, and then bends adorally over the outer slope. The pores are 
transversely oval, the outer one being the more elongate. The inner pore is bounded 
on its adapical margin by a ridge, and is separated from the outer pore by a slight 
elevation, but its adoral margin is depressed, and a slight groove passes from it 
along the suture. This groove, however, thins out as it comes level with the outer pore, 
for the margin of this pore is elevated all round, though stouter on the adapical side. 
The sutural groove then widens suddenly just on the angle of the bend, and again 
thins out towards the outer edge of the ambulacrum. On the outer slope another groove 
arises at a little distance from the outer pore, and this too becomes less marked towards 
the outer edge of the ambulacrum. These two grooves do not die out sufficiently 
to prevent the margin of the ambulacrum being scolloped, with two convex curves 
to each ambulacral. 
Relations of the Specimen. — The outer slope of the ambulacrals 
bears witness to a flexible adradial suture of the type characterising Triado- 
cidaris and Miocidaris, while the disposition of the pores and of the grooves 
leading from them departs but slightly from that described in Triadocidaris 
persimilis. The species, however was evolving, not along the Cidarid line, but 
along that leading to the Diadematidae. 
Diadematoid ambulacrum, ( 
U 
(Plate IX, figs. 216, 217). 
Material. — Fragment of an ambulacrum from bed e 3 of Section VI at 
Veszprém. Cassian age. 
Description of the Specimen. The fragment contains about 19 complete 
ambulacrals on each side, occupying a length of 5.8 mm. measured along the chord 
of the curve, which has a shortradius. The greatest width of the ambulacrum is 2.5 mm. 
The interradial tract is ornamented differently in the adapical and adoral regions. In the 
adapical region, which comprises 7 or 8 ambulacrals on each side, each ambulacral bears 
amain tubercle, and the space between the two meridional rows thus formed is occupied 
1! 
