ICIINOLOGY (ante). The fossil footprints, or ichnolites, of crustaceans are very numerous in America. Dr. Dawson has given much attention to this study. In observ ing the habits of the king crab lie found that in walking over a sandy beach it /link( a marks like those called protichnites (see ante). In the sandstone beds which contain the protichnites are ladder-like impressions called elimactichnites, and Dr. Dawson has shown that probably they are the marks made by the same crustacean, when swimming, which, when walking, produced the protichnites. The ichnolites found in the eocene of the Paris basin are numerous, the most notable being the trilobed footprints of several species of paleotherium (q.v.), and also those of onoplotherium (q.v.).
Great interest attaches to the footprints in the mesozoic rocks of the Connecticut valley from the fact that a majority of the tracks formerly supposed to have been made by birds were made, as shown by prof. Edward Hitchcock, by a huge batrachian, of frog-like animal. In Ins report published by the state of Massachusetts in 1836 lie state* that he had found ichnolites in the new red sandstone in 38 localities. In all there were the footprints of no less than 119 species of animals, comprising quadrupeds, birds, saurians, batrachians, tortoises, fishes, crustaceans, insects, and storms. Some of tilt surfaces show ripple-marks, and others rain-drop marks. The collection of the Cornice ticut valley ichnolites is now in the museum of Amherst college, and comprises more. than 8,000 distinct tracks. Ichnolites have since been found in the same formation in New Jersey, and in the lower triassie sandstones of Lancashire and Cheshire in Englond. and in Hildburghausen, Saxony. The European footprints somewhat resemble an
impression of the human hand, and for a while were supposed to be the footprints of a quadruped called eheirotheriam, belonging to the kangaroo family. It is now, however, thought that the tracks are those of a crocodilean called iabyrinModon.
(Gr. fish-spear stone), the name given to fossil fish spines, that are not uncommon in stratified rocks. Plagiostomous fishes have their dorsal fin furnished in front with a strong bony spine. The fin is connected with the spine. and is elevated and depressed by It seems also to be employed by the fish as a defense against its larger foes. Some bony fishes have similar spines, as the stickle backs, silurids, etc. The spines are most frequently unassociated with any fish remains, having belonged to plagiostomous fish, in which the spine is simply implanted in the flesh, and consequently would be speedily separated from the body of the fish when it began to decompose.
The earliest certain evidence of vertebrate animals is the spines of plagiostomous cartilaginous fishes which occur in the bone brd of the Ludlow rocks, the uppermost of the silurian deposits. Spines belonging apparently to three species have been limed, they are small, compressed, slightly curved, and finely grooved lengthwise. and belong to the genus onchus. Along with them have been found petrified portions of tubercular and prickly skin, like the shagreen of the shark.
The old red sandstone has supplied such a variety of spines as to have afforded the materials for establishing fourteen genera, and in the coal measures they are more numerous, belonging to no less than twenty-one genera.