I-CHANG. 437 ICHTHYODORULITES. the course of the year, the river being practically the only way of reaching the great province of Szf-chuen (where the riel>est coal-fields in the world are situated), and the northern parts of Kweichow and Yunnan. The population of 1 Ch;iii^' is 35,000, including a score or more of foreigners. ICH BIEN, IK den (Ger., I serve) . The motto of the Prince of Wales, which, surmounted by three ostrich-feathers (originally one), forms lis official crest. According to one theory of its i.!criation lidward I. on presenting his new-born ^on, Edward of Carnarvon, to the Welsh, who had demanded a native-born prince, used the ex- pression in its Welsh signification — Eich dyn, "Behold your man." Another view, not his- torically verified, attributes it to the occasion of the killing of John, King of Bohemia, by the ICngli^li at Crecy. and asserts that the Black Prince found the motto under the plume worn by the dead King, and assumed it to imply that "he served iiiuler the King, his father.' ICHNEUMON, ik-nu'mOn (Lat., from Gk. ixvfv^tMiv, ichntntiiii'in, trncker. from Ixytyfty, ich- }tt?uci)i, to track, from Vx""*. ichnos, track). An old name for the civets of the genus Herpestes, now generally called mungooses. (See MuN- c.oosE. ) The name belongs specifically to the Egj'ptian muiigoose, or "Pharaoh's rat' {Herpestes irhiieumon) . ICHNEUMON-FLY. An insect of a group (if |):nasitie llymonoplera, forming the family Iclmeumonida^. Jlore than 1100 genera of ichneu- mon-flies have been described, and many thou- sands of species. Economically considered they are among the most important groups of insects, since without exception they are parasitic upon or within other insects, and in the very great ma- jority of instances they destroy injurious species. As a rule the ichneumon-fly lays her eggs beneath the skin of the host insect. The egg hatches, and the young footless grub feeds upon the fat and blood and lymph of the host, piercing the fatty tis- sue with a pair of sharp-point«d jaws. It re- A LARQE ICHNEUMON-FLy. Male (/j) and f<^inale (a) o( tluiJessa liinator, in relative slze.the latter in the act of forcin;^ her ovipositor into a log. spects the viscera and vital organs of the host up to the last limit, and only sacrifices them toward the completion of its growth. Its skin is very delicate, and it breathes by absorbing oxygen through this skin from the blood of the host in- sect, and not. as the older writers supposed, by placing itself in communication with the trachce of the host. The digestive tube has a very large stomach which is closed behind, and remains closed until the larva is full grown. When this time is reached, and the larva transforms to pupa, a rectiil opening is formed, and the excre- ment is voided. That such an economy as this is necessary to the life of the parasitic larva is at once seen when we consider that if the excre- )nent were voided dailj' it would cause speedy in- fiammation and the death of the host insect be- fore the parasite could become mature. It was formerly supposed that for this same reason the parasitic larva did not cast its skin, but Seurat has recently shown that some of them do occasionally molt. Some ichneumon-fiies lay their eggs on the skin of the insects they attack, and others near the host insect, so that the parasitic larva, after hatching, finds its way to its prey. When the host insect is an internal feeder, like a wood- borer or a gall-insect, the ichneumon larva lives upon instead of within the host. There is no uni- formity in the degree of rapidity with which they develop, and they may pass the winter months cither as larvie, pupa or adults. As a rule they are long-bodied, slender insects, varying much in size. Many of them have long, sting-like oviposi- tors — in some instances, as in Rhyssa, more than twice as long as the body. Both the scientific and popular names of this group of insects were derived from the Egyptian ichneumon or 'Pharaoh's rat.' which devours the eggs and young of the crocodile. Consult: Sharp, Cambridge 'Natural History, vol. V. (London, ISll.j); Comstock. Manual for the Htudy of Insects (Ithaca. 1885) ; Ashmead, "Classification of the Ichneumon-Flies." in Pro- ceedinqs of the United Htatcs Xiitionnl Museum (Washington, 1900). See Colored Plate of In- sects. ICHNOLOGY, ik-noro-ji (from Gk. fx^of, irhitos, trace -f -Xo7ia, -logia, account, from X^ciK, Icijein. to say). The study of fossil foot- prints, tracks, trails, and impressions found in (he rocks of various geological ages. Tlic mo.st prolific sources of such footprints and impres- sions in North America are the .lura-Trias sand- .stones of Massachusetts. Connecticut, and New Jersey. Prof. Edward Hitchcock gathered a great collection of them from the Xew England localities and placed it in the Amherst College Museum. This collection contains over 8000 tracks, and it furnished the material for Hitch- cock's Ichnologij of Xeir England: A Report on the Sandstone of the Connecticut Vallct/. Espe- ciallg Its Fossil Footmarks. JIany of the tracks therein described were first supposed to have been made by birds, but they are now knomi to be the footprints of ornithopod dinosaurs like Anchisaurus (q.v. ). Still others were made by liea'y five-toed animals of unknown nature. Some of the smaller tracks were made by insect larvfe which are found in the same series of deposits. (See MoRMOHCOiDES.) For an entertaining ac- count of fossil footprints, sec the chapter on "Impressions of the Past." in T.ucas. Animals of the Past (New York. 1901). See Fossil: Jvras- .sic System : Tri.ssio SvsTEjr. ICHTHYODOR'ULITES (Neo-Lat. nom. pi., from Gk. I'x^;. ichthys. fish -f- S6pv, dory, spear -|- X(9or-, lilhns, stone). The fossil spines of sharks, which are often found isolated in the ancient rocks. Many of them are of large size, and because of their hardness and phosphatic natiire have been presen'cd with a considerable degree of perfection. Some of them are well
