50 Triassic Echinoderms of Bakony. 
The following are measurements of hypozygals in millimetres: 
Diameters cus. 10) saeeeeOre 41 45 a4 a7 6:0 66 
lnubing, Gummi 6. oo) .¢ OE) 08 0:9 "1 11 11 11 
Diam. = 100, height = _ ._—Ss_-28 19 20 20 19 18 16 
Taking the diameter as 100, the average height of an internodal, as deduced 
from 20 specimens, is 21. But if the adults, with diameter from 45 to 67 
mm., be considered apart, then the average height, as deduced from 9 specimens, 
is 16°7. The average height of adult nodals, as deduced from 8 specimens of 
corresponding size, is 24°75, while the average height of 5 hypozygals of 
corresponding size is 186. It follows from the above measurements that relative 
height decreases with age at about the same rate in normal columnals and hypo- 
zygals, but less rapidly in the case of nodals. The relative height of the nodals is 
nearly 3/2 that of normal columnals; thus, taking an individual specimen, a nodal- 
of height 1°3 mm. is adjacent to internodals of 094 mm average height. The 
hypozygals are a little higher than ordinary internodals of corresponding diameter. 
The variation in height of adjacent normal internodals is slight; occasionally 
they may differ as much as 0°9 and 11 mm. Regular alternation cannot as a rule 
be detected, possibly because the fragments are not long enough, all being under 
11 ossicles in length, except one, whereas the complete intersyzygia must have 
been much longer. The one exception consists of 15 columnals, beginning with an 
epizygal, but not reaching the hypozygal; counting from, but not including, the 
epizygal, every fourth internodal is slightly higher than the rest, while the first and 
third appear in each case to be very slightly lower than the second; thus there 
are four orders of columnals, the nodals being order I. The evidence for the length 
of the internodes is indirect, since no complete intersyzygium has been found. But 
the fact that fragments of 15, 11, and fewer columnals occur with no more than 
one nodal, shows that they must have had a length exceeding those numbers. 
This is confirmed by the relative rarity of epizygals and hypozygals; thus the 
bulk of the material from the most prolific locality consists of: 
Fragments of all sizes without epizygals or hypozygals 302 
> > 2 a )ywithsepizyeals’ [Ga pers) cise em 
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Notala =) aono 
Side-faces smooth, usually slightly convex, but almost straight in some stellate 
and pentagonal forms. There is no tendency for a median ridge to be developed. 
Nodals not swollen. 
Suture-lines depressed, with a distinct cavity in the re-entrant angles; but 
the sutural edges bounding this are not quite regular, there being frequently a 
marginal swelling which tends to divide the cavity into two. Crenelation of the 
suture-line is most clearly seen in concavi-stellate forms, but even here it is some- 
what obscured by the depression and by the partial confluence of the crenellae; in 
other forms it is seen only at the interradial angles, and then but obscurely. 
Joint-faces. — Normal (figs. 103, 111): Lumen minute, subcircular. Central area 
