66 Triassic Echinoderms of Bakony. 
Orper- CTD AR OLD 
Famity: TIARECHINIDAE. 
For diagnosis, vide infra, p. 67. 
Tiarechinus. 
1881. Haueria G. C. Latse. MS., cit. NEUMAYR, op. cit. infra, p. 170. 
1881. Tiarechinus M. NeuMAyR, Sitzber. k. Akad. Wiss. Wien, LXXXIV, Abth. I, p. 169. 
See also: 
1883. A. AGassiz, ,Blake Echini*, Mem. Mus. Harvard, X, No. 1, p. 22. 
1883. S. Loven, «Pourtalesia», Svensk Vet.-Akad. Handl. XIX, Mem. No. 7, pp. 11, 64, pl. XIII. 
1889. P. M. Duncan, «Revision of Echinoidea», J. Linn. Soc., Zool. XXIII, p. 19. 
1889. M..NeumAyYR, «Die Stamme des Thierreiches», p. 365. 
1896. R. T. Jackson, «Studies of Palaeechinoidea», Bull. Geol. Soc. Amer., VII, p. 243, & table annexed. 
1897. J. W. Grecory, Proc. Zool. Soc. London, 1896, p. 1000. 
1900. J. W. Grecory, «Treatise on Zoology», ed. LANKESTER, III, Echinoderma, p. 305. 
1900. J. LaMBERT, Bull, Soc. Sci. Yonne, LIII, p. 44, & Tableau B. 
1903. K. A. v. ZirTeL, «Grundziige der Palaeontologie» 2e. Aufl., p. 206. 
1904. Y. DELAGE & E. HEROUARD, »Traité de Zool. concréte», III, p. 219. 
Before giving the diagnosis, it is necessary to discuss the systematic 
position of the genus. 
Neumayr (1881) rejected the name Haueria «da schon eine Hauera UNGER 
und eine Hauerina Ors. existirt»>. It does not appear that Haueria has ever yet 
been used, and now presumably, thanks to Neumayr’s action, it never can be 
adopted for any animal. 
The genotype and only known species is Tiarechinus princeps Neumayr (1881, 
ex Laube MS.), which has been admirably described by Neumayr (loc. cit.) and by 
Loven (1883). Duncan (1889) founded for the genus the Order Plesiocidaroida, which 
was retained by Prof. Jackson (1896) and redefined by Dr. Grecory in his interesting 
paper on Lysechinus (1897) as well as in 1900. Though the establishment of the 
Order may have been justified by the sudden jump from 1 to 3 interambulacrals 
in Tiarechinus, it is hard to see why Grecory retained it, realising as he did that, 
as regards the interambulacral plates, his genus Lysechinus, if correctly interpreted 
by him, «bridges the gap between Tiarechinus and the Palaeozoic Echinids», and 
that the preponderance of the apical system is not an ancestral character. NEUMAYR 
(1881, p. 174) provisionally placed Tiarechinus in the Archaeocidaridae; but in 
1889, when he fully discussed the question, he merely regarded the genus as better 
referred to the Palaechinoids than to the Euechinoids, a conclusion carried into 
effect by Professors DeLtace and Herovarp (March, 1904). Except for Neumayr’s 
reference to the Archaeocidaridae, unfortunately overlooked by Grecory, no one has 
yet claimed any Family of Palaeozoic Echinoidea for the ancestors of Tiarechinus. 
Whether Dr Grecory’s interpretation of the fossil on which he founded his Lyse- 
chinus be correct or no (and I ought to say that I have utterly failed to verify it 
after repeated efforts), at all events it is theoretically plausible, and it suggests to 
me that the most probable ancestors were the Lepidocentridae. The flexibility of 
the test in that Family is so strongly contrasted with the rigidity of Tiarechinus, 
that the suggestion may seem absurd; but, as may be gathered from Jackson's 
excellent paper (1896), there is no essential difference as regards more important 
morphological features. On this hypothesis the Tiarechinidae would form a Family 
of Grecory’s Order Cidaroida, which is thus defined (1900, p. 301): «Echinoidea 
