100 : Triassic Echinoderms of Bakony. 
Orper: DIADEMOIDA. 
Sus-OrpEer: CALYCINA. 
Famity ACROSALENIIDAE. 
For definitions of the Order, Sub-Order, and Family, see J. W. Grecory (1900., op. cit. infra, p- 306.) 
Eodiadema. 
1889. Eodiadema P. M. DuNcaAN in E. Witson, Geol. Mag. (n. s.), dec. III, vol. VI, p. 339; Aug. 
1889. Eodiadema P. M. Duncan, «Revision of Echinoidea», Journ. Linn. Soc., Zool., XXIII, p. 81. 
1900. Eodiadema DuNcaN em. J. LAMBERT, Bull. Soc. Sci. Yonne, LIII, (1) p. 34. 
See also: 
1900. J. W. GreGoRY, «Treatise on Zoology», ed. LANKESTER, III, Echinoderma, p. 308. 
1904. Y. DELAGE & E. HERouaRD, «Traité de Zool. concréte», III, p. 230. 
1907. A. R. Horwoop, Geol. Mag. (n. s.), dec. V, vol. IV, p. 462. 
Diagnosis. — An Acrosaleniid with ambulacra composed of simple primaries 
with unigeminal pores, except in the extreme adoral region where they become 
arranged in triads and are in part bigeminal; a single perforate tubercle is borne 
by each ambulacral in the adapical region, but only by the second of each triad 
in the adoral region. Main interambulacral tubercles perforate, crenelate, slightly 
eccentric towads the ambulacrum. Other tubercles minute or only miliaries. Apical 
system extended, hemiolicyclic, the posterior genital being separated from the rest 
by intercalated oculars. 
This diagnosis differs slightly from the lengthy one given by Duncan (1889), 
and still more from the concise one of Lampert (1900). It is based on a renewed 
study of the genotype and of other species. 
The genotype is the species described by E. Wuson (1889, loc. cit. supra) 
under the name «Kodiadema granulata> |sic], and depicted by A.S. Foorp in figures 
5, 5a—c of pl. X. illustrating the paper by Witson & Crick on «The Lias Marlstone of 
Tilton, Leicestershire» (tom. cit. pp 296—305 and 337—342). The two specimens 
figured, the only syntypes, are in the collection of the late W. D. Crick, and have 
been lent to me through the kindness of Mr. W. Crick of St. Giles Street, North- 
ampton. Of these two I hereby take the complete test drawn in figs. 5, 5a (loc. cit.) 
as lectotype. According to Mr. A. R. Horwoop (1907) the syntypes and other 
specimens since found came from the Transition bed between the Middle and Upper 
Lias, i. e. above the zone of Amaltheus spinatus. 
Mr. Lampert (1900), who was unacquainted with Witson’s description of the geno- 
type, thought it well to select Echinus minutus BuckMAN as «second type du genre». 
His account of the radioles is doubtless based on that species, and to it also we 
must look for the explanation of certain important divergences from Duncan’s 
diagnosis. Thus, instead of the ambulacrals bearing «trés petits tubercules granuli- 
formes [Auct. MS. corr. pro «granuliferes»]», Duncan says that at the ambitus the 
ambulacrals bear «very small crenulate and perforate tubercles which diminish 
actinally». Also Duncan describes the peristome as «small, and with well-marked 
branchial incisions». LAMBERT says the converse, but possibly intends the same 
thing; for words like «small», «faible» and «well-marked» are meaningless to all 
except their user. In the genotype the diameter of the peristome is circa “4 that of the test. 
Duncan placed Eodiadema in Diadematidae Orthopsinae. Lampert, however, 
who regards the genus as equivalent to the «Criniferen» of QuensrepT (1875, p. 
