Chambers's encyclopædia; a dictionary of universal knowledge . ICHTHYODOTvULITE (Gr. fish-spear-stone),the name given to fossil fish spines, that are notuncommon in the stratifieil rocks. PlagiostomousHshes have theu- dorsal fin furnished in front ^vitha strong bony spine. The fin is connected with thespine, and is elevated and dej^ressed by its move-ment. It seems also to be employed liy the fish asa defence against its larger foes. Some bony fisheshave similar sjiines, as the Sticklebacks, Silimds, & spines are most frequently iinassociated withany fish remains, having belonged to plagi
Chambers's encyclopædia; a dictionary of universal knowledge . ICHTHYODOTvULITE (Gr. fish-spear-stone),the name given to fossil fish spines, that are notuncommon in the stratifieil rocks. PlagiostomousHshes have theu- dorsal fin furnished in front ^vitha strong bony spine. The fin is connected with thespine, and is elevated and dej^ressed by its move-ment. It seems also to be employed liy the fish asa defence against its larger foes. Some bony fisheshave similar sjiines, as the Sticklebacks, Silimds, & spines are most frequently iinassociated withany fish remains, having belonged to plagiostomousfish, in which the spine is simply implanted in theflesh, and consequently would be speedily separatedfrom the body of the fish when it began todecompose. The earliest certain evidence of vertebrate animalsis the spines of plagiostomous cartilaginous fisheswhich occur in the bone bed of the Ludlow rocks,the uppermost of the Silurian deposits. Spinesbelonging apparently to three species have beenfomid; they are small, compressed, slightly Fig. 4.—Footprints of Birds: On the Oolitic Sandstones of Connecticut. ICHTHYOLOGY—ICHTHYOSIS. and finely grooved lengthwise, and belong to thegenus Onehns. Along with them have been foundpetrified portions of tuloerciilar and prickly skin, likethe shagi-een of the shark. The Old Red Sandstone has supplied such avariety of sj^ines as to have afforded the materialsfor establishing fourteen genera, and in the CoalMeasures they are more numerous, belongiug to noless than twenty-one genera. ICHTHYOLOGY (Gr. ichthjs, a fish; logos, adiscourse), that branch of natural history Avhichtreats of Aristotle is the most ancient authorhaving any claim to be noticed in a history ofichthyology, nor was this science much indebtedto any other of the ancients. In modern times, itliegau to be cultivated, about the middle of the16th c, by Belou, Rondelet, and Salviani. Towardsthe close of the 17th c, it made great progressthrough the
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