ICHTHYODOBTTLITES. 438 ICHTHYOSAURUS. alonjj with reninin-i of Ili'spiTornis, Aptomis, and the like. These two ^.a-nera represent the division Odontotormte of the toothed l)irds (see I?rui), r'"o.s.sn.). chiirneterizeil by hnvin<r the ti'i'th, with which tliu niundibles were pU-ntifully furnished, set each in a .separate alveolar soeket. The varimis species were birds not preater than a pigeon in size, and resembling terns in general appearance and probably in habits. They were sea-birds of powerful flight, and the strmtiire of their winga, legs, and carinate sterniuii niucU known under the names of C'tenacanthus, Ma- Cttracanthus, Pleuracanthus, Cyracanthus, etc. Some of these spines have been found in their origin:il positions at the front edges of the fins of fossil sharks .See kjiiAHK ICHTHYOL, ik'tht-61 (from fJk. IxBik, ich- thi/.i. fish ) , or .^mmo.num Ichtiiyoi. Siu'honate. A dark-red oily liquid obtained from a bitumi- nous quartz rich in fossil n*h. fouiiil in the Tyrol. To prepare the drug, the mineral is distilled with strong sulphuric acid, a saturated aqueous solu- tion of common salt is added to the distillate, and the ichtbyol- sulphonic acid which sei)arate3 out is neutriilized with ammo- nia. The icbthyol thus obtained has a somewhat disagreeable bituminois o<Inr and taste, and is sohible in ivater. in glycerin, and in various oils. It is an antiseptic, mild irritant, and somewhat of a stj'ptic. It is absorbed with ease by the skin when applied externally, and by the intestinal mucous mem- brane when administered inter- nally. It is one of the best- known remedies for erysipelas, „„.„.,..,.„.,„.... ... .. ..... BKl LL OF ICHTIiVOR.MS. in Which disease it is applied a. Cranhmi and uppi-r mandible ol /cil/norB/g rc«-.iH«,- fc, lon-or mandible ot externally in the form of an omt- the larger IchtbyorBls victor. ment made up with lanolin. The same preparation is highly recommended for cases of acute articular rheumatism, as alTording prompt relief by reducing the pain and the swell- ing. Unna has declared it to be the remedy par excellence in acne. He applies it externally in the form of a 1.5 per cent, ointment, and gives it internally in do.scs of from - to 10 grains in pills or in capsules; he also recommends the free use of icbthyol soap. Ichthyol is extensively employed in the treatment of various skin dis- eases, and is said to be particularly efScacious in eczema, chronic urticaria, and simple sycosis. It is frequently prescribed, with success, as a local applicati<in in chnmic nasal catarrh, espe- cially in the form known as ulcerative rhinitis. ICHTHYOLOGY, ik'thi-6l'6-jl (Gk./xWi, ich- thys, lish + -Xcryia, -logia, account, from X^eiv. legein, to say). That branch of natural history which treats of fishes. Sec l'"isn. ICHTHYOPHAGI, tk'thl-of'fi-ji (Lat. nom. pi., from (ik. 'Ix0vo<pd:.os. Ichllniophafios, fish- fater, from lx9it. irhlhit.i. (ish 4- (payelv. pha- gein, to cat), .■mong the ancient Greeks, a name for various tribes of coast dwellers on the south- ern seas; in .sia. on the coast of Southern China, Gedrosia, and Northeastern Arabia: in .Africa, on the west coast of the Arabian Gulf and in Senegambia. ICHTHYOPSIDA, Ik'thl-fip'sl-dft (Neo-Lat., from Gk. txdvs. irhthys, fish + O^is, opsis, ap- pearance). A division of the Vertebrata, in- cluding all such forms as have no amnion and alantois, but which have, cither persistently or temporarily, gills as their respiratory organs. The group includes the Amphibia (q.v.) and the fish-like forms. This division was introduced by Huxley. ICHTHYORNIS, Ik'thl-Or'nls (Neo-Lat., from txSii, ichthys, fish + (Spwt, oriii.s, bird). A genus of toothed birds of the Cretaceous age, found fossil numerously in western Kansas, resembles that of modern birds. The skull, how- ever, retains many reptilian features besides tho teeth, such as the diminutive elongated space for the brain, the single-headed quadrate bone, and the union of the lower jaws in front by a ligament. The vertebra?, also, ditfer from those of Hcsperornis and all modern birds, in being biconcave. This form of vertebra is seen in a few recent and many extinct reptiles, but is espe- cially characteristic of fishes; the presence of this character alone would indicate the very an- tique origin of the group. These birds doubtless lived and fed as do modern gulls, seizing living fishes, and going ashore only to breed and roost at night. They were doubtless well feathered, and seem to have fiourished until the end of the Cretaceous era. Most of the fossil remains thus far obtained are in the museums of Yale Uni- versity and of the University of Kansas. See IIkspkrornis; and consult the authorities there referred to. ICHTHYOSAURUS, ik'thi-6-sn'rus ( Xeo- Lat.. Irnm Gk. Ix9lit. ichthys, fish -{- cavpot, sauros, lizard). An extinct genus of fish-like reptiles found in the Mesozoic rocks of Europe and Xorth .Vmerica. The ichthyosaurs among reptiles are analogous to the whales among mam- mals, and they have many points of resemblance to these. Their bodies were round and tapering, heads large, with long snouts and very short necks, limbs reduced to paddles, and they had a broad, vertical tin on the tail and a triangular fin at the middle of the back. The body was covered with thin, smooth skin and no traces of dermal plates have been discovered. The jaws were armed with a large number of sharp, conical teeth that have a complicated internal structure similar to that of the teeth of Lahyrinthodonts or Stegocephalia. The eyes are surrounded by circles of sclerotic bones, and there is a large pineal foramen on top of the skull between the e3'es. The vertebra; are biconcave, and the pelvic
