Echinoid Radioles. Cidaris alata. 
171 
Cidaris sp. A. v. Klipstein, 1843: Geol. Östlich. Alpen, p. 273, pl. xviii, f. 14 a—g [C. dlata apud 
Laube, C. semicostata apud Broili]. 
Cidaris d'Orbignyiana A v. Klipstein, 1843: Geol. Östlich. Alpen, pl. xviii, f. 5: non C. orbignyana 
Ag. 1840. Synn.: C. Klipsteini, J. Marcou, 1847, in Agassiz & Desor : Catal. raisonn. Ech. 
p. 140 (non C. Klipsteini Desor, 18551. C. ampla, Desor, 1858: Synopsis des Echinides 
p 484 [C. semicos'.ata apud Laube et Broii.i1. 
Cidaris perplexa Desor, 1855: Synopsis des Echinides, p. 21, pl. ii, f. 15. Syn. : Cidaris spinulosa 
A. v. Klipstein, 1843: Geol. Östlich Alpen, p. 271, pl xviii, f. 10 a—c (non d — g) (non C. 
spinulosa Ag. 1847; [C. semicostata, apud Laube, Hesse, Broili], 
Cidaris dorsata Bronn in Münster, 1841: Beitr. z. Petrefactenk. IV, pp. 16 & 46, pl. iv, f. 1 a — g. 
[C. alata, apud Agassiz, Desor, Marcou. Koechlin-Schlumherger, on the other hand, 
referred C. alata, C. semicostata, et al. to C. dorsata.\ 
Cidaris austriaca Desor, 1855. Synops. Ech. foss. p. 20, pl. ii, f. 14. Syn. : C. ovifera, A. v. 
Kupstein, 1843 : Geol. Östlich Alpen, p. 271, pl. xviii, f. 8 a, b, non Agassiz \C. semicostata 
apud Laube et Broii.i.] 
This is not the place in which to discuss the above references. Suffice it to 
say that in the case of Klipstein’s species my opinions are based on a study of 
his original specimens in the British Museum, which have, it appears, not been seen 
by previous writers. I have also examined the Originals of Münster, Laube, and 
Broili, as well as the abundant material in the British Museum, collected mainly 
by Klipstein. The most important specimens are, of course, the syntypes of Agassiz. 
Of these the Zoological Department of the British Museum possesses four plaster 
casts, bearing the numbers X8, XI1, XI4, X23, as attached by Agassiz. 
The two decisions that have an immediately practical bearing are the inclusion 
of C. semicostata in C. alata, and the exclusion of C. dorsata. These need 
some defence. 
The radioles termed Cidaris semicostata appear to be the smaller radioles froni the 
oral region of individuals that bore the normal forms of C. alata in the ambital 
region. The two forms are similar in minute structure, as shown by Hesse (op. cit. 
p. 230), and have been separated because of some supposed differences in shape 
or Ornament. It is not easy, however, to gather from the published diagnoses and 
descriptions what the distinction may be. 
Comparison of Münster's two diagnoses shows that the only character peculiar 
to C. semicostata is the presence of four or five sharp longitudinal ribs on the 
distal half of the adoral face ; while the only character contined to C. alata is the 
possession of a sharp keel on each side. The text is clear enough but does not 
harmonise with the plates: Hg. 20 b of C. semicostata has at most indications of 
two ridges ; while the ridges of C. alata Hg. 2 f are scarcely to be distinguished 
from those of C. semicostata Hg 20 a. Again, the lateral keels in C. alata Hgs. 2 f & d 
do not appear very different from the sharp flattened sides clearly indicated in both 
figures of C. semicostata. 
Laube’s diagnoses are sufficiently distinct, but are contradicted by his own 
descriptions and Hgures, as well as by those of Münster. Thus C. alata has «colli 
brevi», while C. semicostata has »collis longus« ; but the description of C. alata 
says «deutliche lange Hals». Laube’s figures show the collerette (Hals) of C. alata 
as long as, or even longer than, in C. semicostata. Then under C. alata 
one reads «facie granulosa», and under C. semicostata «facies glabra vel striata» ; 
since the adapical surface is almost invariably granulär in these radioles, the word 
«facies» can only refer to the adoral surface; but we are told that in some radioles 
