30 Triassic Echinoderms of Bakony. 
The height of a columnal or a cirral is theoretically the distance between two 
planes laid flat on the joint-faces ; but since the crenellae inosculate, this would make the 
height of an internode less than the sum of the heights of its internodals. Moreover, since 
columnals are rarely isolated, they can rarely be measured in this way. For the comparison 
of one specimen with another, one has to take the average of several successive columnals, 
thus compensating for inequalities of growth. When columns are curved the measurement 
on the convex side is greater than that on the concave, and the mean of the two is taken. 
The measurements given in this memoir have been made with sliding callipers, reading 
accurately by a vernier to tenths of a millimetre. The calculations from these measurements 
have rarely been carried beyond the second decimal place. 
In the number of internodals, the hypozygal is included ; in other words, internode + epi- 
zygal —=intersyzygium. 
Isocrinus. 
1767. Isis (pars) LINNAEUS: Syst. Nat., Ed. XII, tom. 1, pars 2, p. 1288. 
1801. Encrinus (pars) LAMARCK: Syst. Anim. sans vertébres, p. 379. Also J. Extis (1762), J. F. BLUMEN- 
BACH (1779—1807), and older authors generally. 
1821. Pentacrinites vel Pentacrinus (pars) J. S. MILLER: Natural History of the Crinoidea, p. 46. Also 
T. and T. Austin (1847), P. H. CARPENTER (1884), and later authors generally. Non Penta- 
crinites J. F. BLUMENBACH (1804). 
1837. Isocrinus H. von MEYER: Mus. Senckenberg. Il, p. 251. 
1852. Cainocrinus E. Forbes: Monogr. Echinodermata British Tertiaries ; Palaeontogr. Soc., p. 33. 
1864. Cenocrinus WyviLLE THOMSON: Intellectual Observer, VI, p. 3. (Not intended as identical with 
Cainocrinus.) 
1864. Neocrinus WyviLLE THOMSON: tom. cit. p. 7. 
1875. Picteticrinus P. de LortoL: Mem. Soc. Phys. Hist. Nat. Geneve, XXIV, p. 297. 
1898. Isocrinus v. MAYER, F. A. BATHER: Nat. Sci., XIL, p. 253. 
The reasons for the above synonymy were so exhaustively discussed in the 
paper last cited («Pentacrinus: a name and its history»), that they need no repetition 
here. The conclusions therein reached have gained quite as much acceptance as 
could be expected, and will therefore be maintained in the present memoir. In 
accordance with them the following well-known Triassic crinoids must now bear 
the name Jsocrinus : — 
Pentacrinus amoenus Lause, 1865, Denkschr. Akad. Wiss. Wien, Math -Nat. 
Cl. XXIV, Abth. 2, p. 277, pl. VIII a, fig. 19 a. [? figs. 19, b, c, and ?? fig. 19 d.] 
The figured specimens are in the Geologische Reichsanstalt, Vienna, where I have 
examined them. I hereby definitely select the specimen drawn in Lause’s fig. 19 a 
as lectotype, since it is doubtful whether the others belong to the same species. 
This species is found in the Cassian beds, and is not represented in the Balaton 
district. 
Pentacrinus bavaricus G. G. Winker, 1861, Zeitschr. d. deutsch. Geol. Ges. 
XIll, p. 486, pl. VIII, fig. 6 a—e. The figured specimens are in the Palaeontological 
Museum, Munich, where I have examined them. That institution has kindly presented 
a paratype to the British Museum (registered E 7105). The species occurs in the 
KGssen beds, and is not known from the Balaton district. 
Pentacrinus Brauniit Monster, 1841, Beitr. z Petrefactenk. IV, p. 50, pl. IV, 
fig. 8 a—d. Lause was most probably correct in regarding this as a synonym of 
