[1] "Placuit picturas in ecclesia esse non debere, ne quod colitur et
adoratur in parietibus depingatur." See Hefele, _Conciliengesch_. i.
170.
[2] The letter, which is most probably, though not certainly,
genuine, appears in the _Acta_ of the second council of Nice.
ICONOSTASIS, the screen in a Greek church which divides the altar and
sanctuary from the rest of the church. It is generally attached to the
first eastern pier or column and rises to the level of the springing of
the vault. The iconostasis or image-bearer has generally three doors,
one on each side of the central door, beyond which is the principal
altar. The screen is subdivided into four or five tiers, each tier
decorated with a series of panels containing representations of the
saints: of these only the heads, hands and feet are painted, the bodies
being covered with embossed metal work, richly gilded. There is a fine
example in the Russo-Greek chapel, Welbeck Street, London, which was
rebuilt in 1864-1865.
ICOSAHEDRON (Gr. [Greek: eikosi], twenty, and [Greek: hedra], a face or
base), in geometry, a solid enclosed by twenty faces. The "regular
icosahedron" is one of the Platonic solids; the "great icosahedron" is a
Kepler-Poinsot solid; and the "truncated icosahedron" is an Archimedean
solid (see POLYHEDRON). In crystallography the icosahedron is a possible
form, but it has not been observed; it is closely simulated by a
combination of the octahedron and pentagonal dodecahedron, which has
twenty triangular faces, but only eight are equilateral, the remaining
twelve being isosceles (see CRYSTALLOGRAPHY).
ICTERUS, a bird so called by classical authors, and supposed by Pliny to
be the same as the _Galgulus_, which is generally identified with the
golden oriole (_Oriolus galbula_).[1] It signified a bird in the plumage
of which yellow or green predominated, and hence Brisson did not take an
unhappy liberty when he applied it in a scientific sense to some birds
of the New World of which the same could be said. These are now held to
constitute a distinct family, _Icteridae_, intermediate it would seem
between the BUNTINGS (q.v.) and STARLINGS (q.v.); and, while many of
them are called troopials (the English equivalent of the French
_Troupiales_, first used by Brisson), others are known as the American
GRACKLES (q.v.). The typical species of _Icterus_ is the _Oriolus
icterus_ of Linnaeus, the _Icterus vulgaris_ of Daudin and modern
ornithologists, an inhabitant of northern Brazil, Guiana, Venezuela,
occasionally visiting some of the Antilles and of the United States.
Thirty-three species of the genus _Icterus_ alone, and more than seventy
others belonging to upwards of a score of genera, are recognized by
Sclater and Salvin (_Nomenclator_, pp. 35-39) as belonging to the
Neotropical Region, though a few of them emigrate to the northward in
summer. _Cassicus_ and _Ostinops_ may perhaps be named as the most
remarkable. They are nearly all gregarious birds, many of them with loud
and in most cases, where they have been observed, with melodious notes,
rendering them favourites in captivity, for they readily learn to
whistle simple tunes. Some have a plumage wholly black, others are
richly clad, as is the well-known Baltimore oriole, golden robin or
hangnest of the United States, _Icterus baltimore_, whose brightly
contrasted black and orange have conferred upon it the name it most
commonly bears in North America, those colours being, says Catesby
(_Birds of Carolina_, i. 48), the tinctures of the armorial bearings of
the Calverts, Lords Baltimore, the original grantees of Maryland, but
probably more correctly those of their liveries. The most divergent form
of _Icteridae_ seems to be that known in the United States as the
meadow-lark, _Sturnella magna_ or _S. ludoviciana_, a bird which in
aspect and habits has considerable resemblance to the larks of the Old
World, _Alaudidae_, to which, however, it has no near affinity, while
_Dolichonyx oryzivorus_, the bobolink or rice-bird, with its very
bunting-like bill, is not much less aberrant. (A. N.)