Echinoid Tests, Diademoida. 103 
the margin is thicker and clearly bevelled, with the denticles on the bevel; this 
probably was more adoral in position. These specimens prove that, as was to be 
expected, there was in the early Diadematidae just the same transition of the adradial 
suture from flexible to rigid as took place in the Cidaridae. Therefore the interest 
of the Triassic species lies less in this obvious differentia than in their relation to 
the known genera of later age, and to place them in fresh genera would not avert 
the need for a comparison between them and genera already established. Further, 
the erection of genera on such imperfect material, without certain knowledge of 
either ambulacra, apical systems, or radioles, would be to court confusion. Con- 
sequently it appears the most profitable line of action to refer each new species 
to that genus which it most resembles in interambulacral structure. 
To avoid repetition under each species, we may here run through the Diad- 
ematid genera or subgenera with perforate non-crenelate tubercles, and eliminate those 
which are obviously different or for other reasons are out of court. Thus we may, 
on a priori grounds, at once exclude genera of which no representative older than 
Cretaceous is yet known We may also legitimately remove from discussion genera 
in which the pore-pairs are distinctly biserial or triserial, first because it is highly 
improbable that such a high stage of evolution should have been reached at this 
period, secondly because such a structure would not harmonise with the denticulate 
adradial margin. Since we have only interambulacrals before us, comparison must 
be restricted to those plates, and it will readily be seen from inspection, of Figures 
192—219 that the Bakony forms cannot well be referred to any of the following 
genera or subgenera, which are here mentioned without any implication as to their 
validity or otherwise. They are taken in the order in which they were first proposed. 
Leptocidaris QurENSTEDT, 1858, genotype L. triceps Quenst., Weisser Jura, certainly 
seems Diadematid in its ambulacra. The interambulacrals are thin, and though 
not numerous, are relatively wide and with a fine granulation only on their 
lateral margins; scrobicules apparently indistinct and confluent. 
Cidaropsis Cotrrau 1863, genotype Hemicidaris minor Ac. 1840, Bathonian and 
Callovian, has main tubercles large and Cidaroid, separated by a wide extent 
of intertubercular miliaries. 
Miopedina Pomet, 1883, genotype Hemtcidaris Matheyi Drsor, Bathonian; to it 
Pomet also refers, without sufficient reason, Hemipedina tuberculosa Wricut, 
Corallian. This genus is superficially like Hemicidaris; the interambulacrals 
relatively high, with large main tubercles in the middle of the plates, the extra- 
scrobicular surface covered with secondaries, tertiaries, and miliaries, which form 
no very definite scrobicular ring. 
Phymopedina Pomet, 1883, genosyntypes Hemipedina marchamensis and H. Bou- 
chardi Wricut, Corallian and Kimmeridgian. This equals Wricut’s Section II of 
Hemipedina, characterized by 4—10 series of nearly equal tubercles on the 
interambulacrum. 
1 DuncaAN (1889, Revision, p. 53) says «Cotteau, 1860 (reference not to be found)». The date 
1860 was probably taken from Correau’s own statement (Pal. Franc. Jurass. Echin. p. 433, Nov., 1882); 
but this appears to be a misprint for 1863, which is given, without further reference, in the synonymy 
five lines lower down. The name was first introduced, without genotype, in a key to the genera of 
Diadematidae (Pal. Franc. cretac. Echin. p. 374, July, 1863). 
