224 
Trias sic Echinoderms of Bakony. 
crushing; adapical radioles of C. dorsata may have a similar ridge round the 
distal end, and it is probably one of them. 
Next to C. trigona, Quenstedt (1875, p. 196), described his Radiolus complanatus, 
previously confused vvith C. Roemeri Although subsequent authors, including 
Quenstedt himself (Handbuch d. Petrefactenk., 1885), have paid no attention to this 
species, examination of the 16G specimens in the British Museum has convinced me 
that Quenstedt was right in separating it. 1t is this species that seems most closely 
nllicd to C. trigona, since it has the same massive shaft, with one face flattened 
and imbricate, the others rounded and granulate. The differences between the two 
lie in the great er average size of R. complanatus, the general smoothness of its 
back, and the angle formed by the axes of the handle and blade Cidaris Roemeri 
is easily distinguished from R. complanatus, but into that question we cannot enter 
novv. It has, however, the imbricate Ornament of C. trigona and R. complanatus, 
only intensified, and we may here recall Quenstedt’s comparison of its shaft to a 
massive Bryozoon. Considering these resemblances, it is the more curious to find 
that neither R. complanatus nor C. Roemeri has the very coarse micro-structure 
of C. trigona. In R. complanatus the septa fork more than in C. trigona, and are 
twice or three times as close (PL XV111, fig. 454). In C. Roemeri the septa not 
only fork, but wave and anastomose; and the structure is fully six times as fine 
as in C. trigona (PL XVIII, fig. 455, 456). 
Cidaris tyrolensis Desor (1855, p. 20, pl. ii, f. 7) was referred by Laube to 
C. Roemeri. The original of Desor’s f. 7a probably belongs to C. Roemeri s. str., 
and the original of his f. 7 b probably belongs to Radiolus complanatus. To 
avoid confusion of nomenclature, I hcreby s'elect the original of Münster, 1841, 
pl. iv, f. 3, e as holotype of Cidaris Roemeri Wissmann in Münst. ; the original of 
Quenstedt, 1875, pl. lxviii, f. 87 a, b, c as holotype of Radiolus complanatus Quenst. ; 
and the original of Desor 1855, pl. ii, f. la (= Münster 1841, pl. iv. f. 3, h) as 
holotype of Cidaris tyrolensis Des. Thus C. tyrolensis becomes a synonym of 
C. Roemeri, and the name R. complanatus is not interfered with. 
Another species that seems to fall into the same group as C. trigona is 
Cidaris Petersi Laube (1865, p. 284, pl. viii b, f. 5), of which I have examined 
the two syntypes at Vienna. The original of Laube’s f. 5 a is hereby selected as 
holotype. 
The Ornament of this species resembles the imbricate Ornament of C. trigona , 
and in the holotype merges into pustules at the distal end ; the difference is that 
the microstructure, as judged from external examination, is filier. Other resemblances 
are found in the small acetabulum with smooth margin, the smooth annulus, and 
the very short collerette. 
In its Ornament, this group of species (C. trigona, C. Roemeri, C. Petersi, 
and R. complanatus) approaches the group of C. flexuosa and its allies; but that 
group differs in having a large axial canal instead of a loose axial complex. The 
internal structure of C. Petersi, however, is still unknown. 
