Echinoid Radioles, Cidaris decorata et fasciculata. 187 
«Cidaris» fasciculata. 
(Plate XII, fig. 343.) 
1843. Cidaris fasciculata A. v. KiipsTEIN, Geol. Ostlich. Alpen, p. 269, pl. xviii, f. 3a—c, and 7. 
1855. Cidaris avena Desor, Synops. Ech. foss., p. 21, pl. ii, f. 25. 
1855. Cidaris fasciculata KLIPSTEIN pars, Desor, Synops. Ech. foss., p. 21, pl. ii, f. 16. 
1865. Cidaris fasciculata KuipsTEIN, G. C. Lauper, Denkschr. Akad. Wiss. Wien, Math,-Naturw. Cl. 
XXIV. Abth. 2, p. 293, pl. x, f. 12. 
Diagnosis. — A Cidaroid with primary radioles subcylindrical or fusiform, 
the supposed peripheral ones ending in an irregular obtuse point often with marked 
ribs which die away into the shaft, where they give place to fine longitudinal ribs 
broken up into granules; collerette varies in relative length, with surface finely 
striate, sides usually concave, ending in a raised distal margin which is usually 
oblique; annulus well-marked, striate, almost straight; acetabulum wide, deep, 
with raised, crenelate margin. 
Notes on Cassian specimens. — The diagnosis is based on the 
eight specimens (syntypes) forming No. 651 of the Kuipsrein Collection in the British 
Museum. Of these I hereby select the original of Kuipstein’s pl. xviii, f. 3 a, b, 
as holotype (regd. E 9412); the original of f. 3, c. is registered E 9413; the ori- 
ginal of f. 7 is the holotype of Cidaris avena Desor (regd. E 4682); the remaining 
five specimens are registered 36495. 
In restoring C. avena to C. fasciculata Laupe was undoubtedly correct, but 
it is not clear why he stigmatised Kuipsrein’s figure 7 as «sehr ungenaue». It is 
true that the specimen now consists of only the distal half, but this agrees closely 
with the figure, and there is no reason to doubt the accuracy of the remaining half. 
Other specimens of C. fasciculata have a collerette and base of similar character. 
KurpsTEIN’s figure 7 represents the specimen from the side of one of the three ribs 
or keels to which it owes its subtriangular section. 
There is little to add to Kutpsretn’s excellent description of his species, but a 
few measurements (in millimetres) will render it more precise. 
) 
i Holotype E 9413 36495 a 36495 b 
Greaiestplenotimmrame at ener er ese ee ee 19°6 11°3 ca 16°5 9:4 
Greatesivdiametee 9). = os 6) ss 46 29 54 3-9 
Greatestulenpihsoicollerettens a.) vue ee 2°8 25 2.0 iCable 
Least + es ee hy, act Vian Pie, 1°7 cay 1:0 1:0 
Least diameter of collerette . . ... . 30 20 Qh Ze 
Diametensatannulsis 4s 8... | 32 2°0 ? one 
Outer diameter of acetabulum . ... . Bio legate: ? iS) 
These measurements show that there is considerable variation in the relative 
thickness of the shaft, and in the relative length of the collerette. 
The ribs of the shaft run 3 to a millimetre on the side of the least length of 
collerette, and from rather less than this down to 2 to a millimetre on the other 
side of the shaft. I cannot decide which face is to be regarded as adoral. These 
ribs are very much coarser than the striae of the collerette, and are homologous 
with the ribs of C. decorata. In fact, where the surface is worn the striae are 
seen on the shaft also, about 8 or 9 going to a rib. 
