Echinoid Radioles , Cidaris decorata et fasciculata. 
187 
« Cidaris » fasciculata. 
(Plate XII, fig. 343.) 
1843. Cidaris fasciculata A. v. Klipstein, Geol. Östlich. Alpen, p. 269, pl. xviii, f. 3 a— 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 Klipstein, G. C. Laube, Denkschr. Akad. Wiss. Wien, Math.-Naturw. CI. 
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 irregulär obtuse point often with marked 
ribs which die away into the shaft, where they give place to hne 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 Klipstein Collection in the British 
Museum. Of these 1 hereby select the original of Klipstein’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. fascicidata Laube was undoubtedly correct, but 
it is not clear why he stigmatised Klipstein’s hgure 7 as «sehr ungenaue». It is 
true that the specimen now consists of only the distal half, but this agrees closely 
with the hgure, 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. 
Klipstein’s hgure 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 Klipstein’s excellent description of his species, but a 
few measurements (in millimetres) will render it more precise. 
Holotype 
E 9413 
36495 a 
36495 b 
Greatest length. 
. . . 19'6 
1L3 
ca 16‘5 
9*4 
Greatest diameter. 
... 4'6 
2-9 
5-4 
3-9 
Greatest length of collerette . . 
... 2-8 
2'5 
2-0 
ca 1*6 
Least » » » . . 
... 22 
17 
ca l'O 
1-0 
Least diameter of collerette . 
... 3-0 
2'0 
27 
2-2 
Diameter at annulus .... 
. . . 3-2 
2-0 
? 
2-2 
Outer diameter of acetabulum . 
. . . 2'5 
1-35 
L5 
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. 
