66 
Triassic Echinoderms of Bakony. 
Order: CIDAROIDA. 
Family: TI A R E C HIN ID A E. 
For diagnosis, vide infra, p. 67. 
Tiarechinus. 
1881. Haueria G. C. Laube. 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. Dukcan, «Revision of Echinoidea», J. Linn. Soc., Zool. XXIII, p. 19. 
1889. M. Neumayr, «Die Stämme des Thierreiches», p. 365. 
1896. R. 1'. Jackson, «Studies of Palaeechinoidea», Bull. Geol. Soc. Amer., VII, p. 243, & table annexed. 
1897. J. W. Gregory, Proc. Zool. Soc. London, 1896, p. 1000. 
1900. J. W. Gregory, «Treatise on Zoology», ed. Lankester, III, Echinoderma, p. 305. 
1900. J. Lambert, Bull. Soc. Sei. Yonne, LIII, p. 44, & Tableau B. 
1903. K. A. v. Zittel, «Grundzüge der Palaeontologie» 2e. Aull., p. 206. 
1904. Y. Delage & E. Herouard, »Traite de Zool. concrete», 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 Orb. 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. Gregory in bis interesting 
paper on Lysechinus (1897) as well as in 1900. Though the establishment of the 
Order may have been justihed by the sudden jump from 1 to 3 interambulacrals 
in Tiarechinus, it is hard to see why Gregory 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 
elTect by Professors Delage and Herouard (Adarch, 1904). Except for Neumayr’s 
reference to the Archaeocidaridae, unfortunately overlooked by Gregory, no one has 
yet claimed any Family of Palaeozoic Echinoidea for the ancestors of Tiarechinus. 
Whether Dr Gregory’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 tlexibility 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 Gregory’s Order Cidaroida, which is thus defined (1900, p. 301): «Echinoidea 
