130 
Trmssic Echinodernis of Bakony. 
Radially placcd between the epiphyses of adjaccnt pyramids are 5 pieces, «quinque 
trabeculae, paria maxillarum coniungentes», as Klein says. His term unfortunately has nevcr 
been adopted ; instead one has to choose from a long series of more or less inappropriate 
or cumbrous expressions. Of these the first is R o t u 1 a, applied by C. Des Moulins 
(1835, p. 232 = 66 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 hoinologous elements in Echinoidea Regularia. Valentin (1841) proposed 
the inappropriate term falx {faux, sichle), 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 Gregory (1900), appears to have been first used 
by A. ÄGASSiz (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 inlerior to its thiee predecessors. The same objection applies to the 
Schaltstück of H. v. Meyer (1849) and the more cumbrous Zwischenkieferstück 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 Macalister (Introd. Anim. 
Morph., 1876) or even of Laternradien used by J. Müller (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 [Anglice : crowbar]) similia, inter trabeculas interposita». (Klein 1734). 
In this sentence «inter» appears to be a mistake for «supra». C. Des Moulins (1835, 
p. 428 = 193 of reprint) described the pieces more correctly as «posees comme des anses de 
panier en dessus et parallelement aux precedentes», but he gave no name. The first name 
was Compass given by Valentin (1841), used by Müller (1854), A. Agassiz (1874), 
Loven (1892), and others, and here adopted. The Germans, following H. v. Meyer (1849) 
often call them Gabelstücke or Bügelstücke ; F. Bernard (1893) adds piece en Y, and 
etrier; Macalister (1876) prefers manubria. Any of these terms are free from ambiguity, 
but it is hard to understand why Duncan (1889) and Lang (1894) gave rotula as a 
synonym, or why Stewart (1861), followed by H. M. Bernard in the translation of 
Lang (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. 
Jerwssdlemhegy ( a ). 
(Plate IX, figs. 220—222.) 
Adoral end of a tooth. Raiblian. 
Grooved, 5'8 mm. long, L7 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 gedrückt werden kann.» J. MÜLLER. 
