Morphological Besults. 
247 
The stem of the same species presents syzygies of an interesting character, 
in the development of a special System of fine crenellae, which overlie or supersede 
the normal crenellae of the joint-face (p. 52). As a rule the syzygial modification 
consists merely in a flattening out and disappearance of the normal crenellae; but 
here is an entirely fresh structure arising. These fine crenellae may be compared 
with the radiating striae that characterise the brachial syzygies of so many of the 
later crinoids. Since there can be no doubt as to the morphological individuality 
and independence of the two components of a columnal syzygy, this may be regarded 
as an additional argument for the independence of the two elements in a brachial 
syzygy. I could never see why the brachial syzygy should be regarded as having 
arisen in a different way from the syzygy in the stem, since the two kinds have 
a similar structure and a similar function. But this is not the place for detailed 
discussion of that controverted question. 
The patina or dorsal cup of an Isocrinus (probably I. scipio), described on 
p 56, owes its chief interest to the fact that it is the only one known from the 
Trias. Though already crypto-dicyclic, it presents features reminiscent of the earlier 
Pentacrinidae and their probable ancestors in the Carboniferous rocks. 
The brachial, probably of an Isocrinus, found in the same Cserhät beds, is 
also primitive in various features (p. 58). 
Towards the anatomy of the Echinoids, the chief contribution is the more 
exact description of the flexible union along the junction of the ambulacrum with 
the interambulacrum, first described by Doederlein. This is here described in species 
of both Triadocidaris and Miocidaris (pp. 69, 73, 81, 85), and is also shown to 
occur in early Diademoids. The main correction is the proof that the denticles of 
the interambulacrals slide in the grooves between the ambulacrals, and not in the 
grooves on the ambulacrals. Thus the denticles on the inner bevelled face of the 
interambulacrals correspond to the projections on the vertical edges of the same 
plates in later Cidarids, and there is no break in the evolution. The gradual nature 
of the evolution is further proved by the Observation that the angle of the bevel 
becomes steeper as the oral end of the suture is approached; in fact the suture 
is nearly if not quite vertical at the level of the perignathic girdle. This latter struc¬ 
ture is here seen in its early development, and it is a fairly obvious inference that 
the mechanical advantage conferred by greater rigidity in this region led to the 
perpetuation of those forms in which the suture was here more vertical; and that 
the change in the nature of the suture gradually extended from here to the adapical 
regions of the test. 
The flexibility so obvious in the adradial suture is regarded as a relic of the 
Streptosomatous condition characteristic of the whole test in so many Palaeozoic 
Echinoids. Other relics of the same condition are found in the sutures between 
the interambulacrals themselves, both in Miocidaris (p. 86) and in Mcsodiadema 
(p. 122). 
Our knowledge of particular genera is advanced most in the case of Anaulo- 
cidaris, which the abundant Bakony material has enabled me to reconstruct in great 
part, and to resuscitate as an independent genus of Cidaridae. Not only have we 
here a complete series of radioles (p. 138), but it is believed that the new species, 
A. testudo, is also represented by several interambulacral plates (p. 94). 
The useful work of Hesse (1900) on the micro-structure of Echinoid radioles 
