The spiral forms were common in the Iron Age of northern Europe, while
silver bracelets of great elegance, formed of plaited and intertwisted
strands of silver wire, and plain penannular hoops, round or
lozenge-shaped in section and tapering to the extremities, became common
towards the close of the pagan period. The late Celtic period in Britain
was characterized by serpent-shaped bracelets and massive armlets, with
projecting ornaments of solid bronze and perforations filled with
enamel. In the middle ages bracelets were much less commonly used in
Europe, but the custom has continued, to prevail among Eastern nations
to the present time, and many of the types that were common in Europe in
prehistoric times are still worn in central Asia.
A treatise, _De Armillis Veterum_, by Thomas Bartholinus, was
published at Amsterdam in 1676.
BRACHIOPODA, an important and well-defined but extremely isolated class
of invertebrates. The group may be defined as follows: Sessile solitary
_Coelomata_ with bivalved shells usually of unequal size and arranged
dorso-ventrally. The head is produced into ciliated arms bearing
tentacles. They reproduce sexually, and with doubtful exceptions are of
separate sexes.
The name Brachiopod ([Greek: brachion], an arm, and [Greek: pous,
podos], a foot) was proposed for the class by F. Cuvier in 1805, and by
A.M.C. Dumeril in 1809, and has since been very extensively adopted. The
division of the group into _Ecardines_ (_Inarticulata_), with no hinge
to the shell and with an alimentary canal open at both ends, and
_Testicardines_ (_Articulata_), with a hinge between the dorsal and
ventral valves and with no anus, was proposed by Owen and has been
adopted by nearly all authors. In a later scheme based on our increased
knowledge of fossil forms, the Brachiopoda are divided into four primary
groups (orders). This is given at the end of the article, but it must
not be forgotten that the existing forms with an anus (Ecardines) differ
markedly from the aproctous members of the group (Testicardines).
[Illustration: Figs. 1-11.--Various forms of Brachiopoda.