the tail-fin is expanded in a vertical plane and has the lower lobe stiffened by the tapering end of the backbone, which is sharply bent downwards. Immature individuals are sometimes observable within the full-grown skeletons, suggesting that this reptile was viviparous.
|From British Museum Guide to Fossil Reptiles and Fishes, by permission of the Trustees.|
|Skeleton of Ichthyosaurus communis, with outline of body and fins,
from the Lower Lias of Lyme Regis, Dorset; original nearly fourmetres in length.
The largest known species of Ichthyosaurus is I. trigonodon from the Upper Lias of Banz, Bavaria, with the head measuring about two metres in length and probably representing an animal not less than ten metres in total length. I. platyodon, from the English Lower Lias, seems to have been almost equally large. I. intermedius and I. communis, which are the commonest species in the English Lower Lias, rarely exceed a length of three or four metres. The species in rocks later than the Lias are known for the most part only by fragments, but the remains of Lower Cretaceous age are noteworthy for their very wide geographical distribution, having been found in Europe, the East Indies, Australia, New Zealand and South America. Allied Ichthyosaurians named Ophthalmosaurus and Baptanodon, from the Upper Jurassic of England and North America, are nearly or quite toothless and have very flexible broad paddles. The earliest known Ichthyosaurians (Mixosaurus), which occur in the Trias, are of diminutive size, with paddles which suggest that these marine reptiles were originally descended from land or marsh animals (see Reptiles).
Authorities.—R. Owen, A Monograph of the Fossil Reptilia of the Liassic Formations, part iii. (Mon. Palaeont. Soc., 1881); E. Fraas, Die Ichthyosaurier der süddeutschen Trias- und Jura-Ablagerungen (Tübingen, 1891). Also good figures in T. Hawkins, The Book of the Great Sea-dragons (London, 1840).
ICHTHYOSIS, or Xeroderma, a general thickening of the whole skin and marked accumulation of the epidermic elements, with atrophy of the sebaceous glands, giving rise to a hard, dry, scaly condition, whence the names, from ἰχθύς, fish, and ξηρός, dry, δέρμα, skin. This disease generally first appears in infancy, and is probably congenital. It differs in intensity and in distribution, and is generally little amenable to any but palliative remedies, such as the regular application of oily substances. Ichthyosis lingualis (“smokers’ tongue”), a variety common in heavy smokers, occurs in opaque white patches on the tongue, gums and roof of the mouth. Cancer occasionally starts from the patches. The affection is obstinate, but may disappear spontaneously.
ICKNIELD STREET. (i) The Saxon name (earlier Icenhylt) of a prehistoric (not Roman) “Ridgeway” along the Berkshire downs and the Chilterns, which crossed the Thames near Streatley and ended somewhere near Tring or Dunstable. In some places there are traces of a double road, one line on the hills and one in the valley below, as if for summer and winter use. No modern highroad follows it for any distance. Antiquaries have supposed that it once ran on to Royston, Newmarket and Norfolk, and have connected its name with the Iceni, the Celtic tribe inhabiting East Anglia before the Roman conquest. But the name does not occur in early documents so far east, and it has certainly nothing to do with that of the Iceni (Haverfield, Victoria History of Norfolk, i. 286). See further Ermine Street. (2) A Roman road which ran through Derby, Lichfield, Birmingham and Alcester is sometimes called Icknield Street and sometimes Rycknield Street. The origin of this nomenclature is very obscure (Vict. Hist. of Warwick, i. 239). (F. J. H.)
ICON (through the Latinized form, from Gr. εἰκών, portrait, image), generally any image or portrait-figure, but specially the term applied to the representations in the Eastern Church of sacred personages, whether in painting or sculpture, and particularly to the small metal plaques in archaic Byzantine style, venerated by the adherents of the Greek Church. See Iconoclasts; Image-Worship; Byzantine Art. The term “iconography,” once confined to the study of engravings (q.v.), is now applied to the history of portrait images in Christian art, though it is also used with a qualifying adjective of Greek, Roman and other art.
ICONIUM (mod. Konia), a city of Asia Minor, the last of the Phrygian land towards Lycaonia, was commonly reckoned to Lycaonia in the Roman time, but retained its old Phrygian connexion and population to a comparatively late date. Its natural surroundings must have made it an important town from the beginning of organized society in this region. It lies in an excellently fertile plain, 6 m. from the Pisidian mountains on the west, with mountains more distant on the north and south, while to the east the dead level plain stretches away for hundreds of miles, though the distant view is interrupted by island-like mountains. Streams from the Pisidian mountains make the land on the south-west and south of the city a garden; but on the east and north-east a great part of the naturally fertile soil is uncultivated. Trees grow nowhere except in the gardens near the city. Irrigation is necessary for productiveness, and the water-supply is now deficient. A much greater supply was available for agriculture in ancient times and might be reintroduced.
Originally a Phrygian city, as almost every authority who has come into contact with the population calls it, and as is implied in Acts xiv. 6, it was in a political sense the chief city of the Lycaonian tetrarchy added to the Galatian country about 165 B.C., and it was part of the Roman province Galatia from 25 B.C. to about A.D. 295. Then it was included in the province Pisidia (as Ammianus Marcellinus describes it) till 372, after which it formed part of the new province Lycaonia so long as the provincial division lasted. Later it was a principal city of the theme of Anatolia. It suffered much from the Arab raids in the three centuries following A.D. 660; its capture in 708 is mentioned, but it never was held as a city of the caliphs. In later Roman and Byzantine times it must have been a large and wealthy city. It was a metropolis and an archbishopric, and one of the earliest councils of the church was held there in A.D. 235. The ecclesiastical organization of Lycaonia and the country round Iconium on all sides was complete in the early 4th century, and monuments of later 3rd and 4th century Christianity are extremely numerous. The history of Christian Iconium is utterly obscure. The city was thrice visited by St Paul, probably in A.D. 47, 50 and 53; and it is the principal scene of the tale of Paul and Thecla (which though apocryphal has certainly some historical basis; see Thecla). There was a distinct Roman element in Iconium, arising doubtless from the presence of Roman traders. This was recognized by Claudius, who granted the honorary title Claudiconium, and by Hadrian, who elevated the city to the rank of a Roman colony about A.D. 130 under the name Colonia Aelia Hadriana Augusta Iconiensium. The period of its greatest splendour was after the conquest by the Seljuk Turks about 1072–1074. It soon became the capital of the Seljuk state, and one of the most brilliant cities of the world. The palace of the sultans and the mosque of Ala ed-dīn Kaikobād formerly covered great part of the Acropolis hill in the northern part of the city. Farther south there is still the great complex of buildings which form the chief seat of the Mevlevi dervishes, a sect widely spread over Anatolia. Many other splendid mosques and royal tombs adorned the city, and justified the Turkish proverb, “See all the world; but see Konia.” The walls, about 2 m. in circumference, consisted of a core of rubble and concrete, coated with ancient stones, inscriptions, sculptures and architectural marbles, forming a striking sight, which no traveller ever examined in detail. Beyond the walls extended the gardens and villas of a prosperous Oriental population, especially on the south-west towards the suburb of Meram.
When the Seljuk state broke up, and the Osmanli or Ottoman sovereignty arose, Konia decayed, its population dwindled and the splendid early Turkish buildings were suffered to go to ruin. As trade and intercourse diminished Konia grew poorer and more ruinous. The walls and the palace, still perfect in the beginning of the 19th century, were gradually pulled down for building material, and in 1882 there remained only a small part of the walls, from which all the outer stones had been removed, while the palace was a ruin. At that time and for some years later a large part of Konia was like a city of the dead. But about 1895 the advent of the Anatolian railway began to restore its prosperity. A good supply of drinking water was