130 Triassic Echinoderms of Bakony. 
Radially placed between the epiphyses of adjacent pyramids are 5 pieces, «quinque 
trabeculae, paria maxillarum coniungentes», as KLEIN says. His term unfortunately has never 
been adopted; instead one has to choose from a long series of more or less inappropriate 
or cumbrous expressions, Of these the first is Rotula, applied by C. Des Moutins 
(1835, p. 283266 of reprint) to these elements in Clypeaster, where they resemble in 
shape the rotula of the human knee; he subsequently (p. 428==193 of reprint) compared 
with these the homologous elements in Echinoidea Regularia. WVaLentin (1841) proposed 
the inappropriate term fala (faux, sickle), being perhaps misled by KLEIn’s phrase «ossicula 
falciformia» applied not to the trabeculae, but, quite happily, to the maxillae. The term 
brace, adopted by Duncan (1889) and Grecory (1900), appears to have been first used 
by A. Acassiz (1874, Revision, p. 688) who, however, still spoke of «the rotulae of the 
Clypeastroids» (p, 689), including in that term the rotula proper and the adjacent epiphyses. 
If the term brace be intended to express the mechanical function of the ossicle,* it must 
be an adaptation from the technical builders’ usage (Murray, Engl. Hist. Dict., sub vocem 
IV, 17). But being without adequate representatives in other languages, notably in Latin, 
it is in this respect inferior to its three predecessors, The same objection applies to the 
Schaltstiick of H. v. Meyer (1849) and the more cumbrous Zwischenkieferstiick of A. LANG 
(Lehrbuch, 1894). Any of the preceding terms may be used without confusion, but the 
same cannot be said of the phrase radial pieces employed by Maca.isTeR (Introd. Anim. 
Morph., 1876) or even of Laternradien used by J. MULLER (1854). The term Rotula is 
adopted here as having priority among those terms that have found acceptance; it was 
used by Loven. 
Remain to be considered «Reliqua ossicula quinque, vecti ferreo, qui ab vngulis vaccinis 
nomen habet (Kuhfuss [Anglicé: crowbar]) similia, inter trabeculas interposita». (KLEIN 1734). 
In this sentence «inter» appears to be a mistake for «supra». C. Des Mou.ins (1835, 
p. 428 = 198 of reprint) described the pieces more correctly as «posées comme des anses de 
panier en dessus et parallélement aux précédentes», but he gave no name. The first name 
was Compass given by VALENTIN (1841), used by Miter (1854), A. Acassiz (1874), 
Loven (1892), and others, and here adopted. The Germans, following H. v. Meyer (1849) 
often call them Gabelstiicke or Biigelstiicke; F. Brrnarp (1893) adds piéce en Y, and 
étrier ; MACALISTER (1876) prefers manubria. Any of these terms are free from ambiguity, 
but it is hard to understand why Duncan (1889) and Lane (1894) gave rotula as a 
synonym, or why Stewart (1861), followed by H. M. Bernarp in the translation of 
Lane (1896), employed the overworn word radius. 
The terminology of the various regions of each element, though extensive and detailed, 
is not particularly confused. Here that introduced chiefly by VALENTIN (1841) and emended 
by Loven (Echinologica, 1892) is followed in the main. 
Ferussdlemhegy (a). 
(Plate IX, figs. 220—222.) 
Adoral end of a tooth. Raiblian. 
Grooved, 5°8 mm. long, 1°7 mm. greatest width; the sides of the groove 
slightly flattened so as to approach a V shape (fig. 221); no sign of striae. The 
area of attachment to the dental slide defined by a slight groove between it and the 
rounded back of the tooth (fig. 220). 
* 
«Durch sie werden die Kiefer so weit aus einander gehalten, dass bei der Action der Zwischenkiefer- 
muskeln der unter der Rotula durchgehende Ambulacralcanal nicht gedriickt werden kann.» J. MULLER. 
