I. Isaac, an American naturalist, born in Wilmington, Del., March 4, 1792. His ancestors followed William Penn from England, and were ministers in the society of Friends. At the age of 15 he was placed with his elder brother, a merchant in Philadelphia, but retained a fondness for natural objects. With Prof. Vanuxem, then a youth, he collected minerals, fossils, etc, and observed the rocks of Pennsylvania. In 1815 both were elected members of the academy of natural sciences of Philadelphia, and Mr. Lea shortly after published his first paper in the " Journal of the Academy," being an account of the minerals which he had observed in the neighborhood of Philadelphia. To a collection of minerals and geological specimens made by his own exertions, those of palaeontology and recent shells were added, which at the present time have grown to great magnitude; that of freshwater shells is entirely unequalled, the family of unionidae alone consisting of about 9,500 selected specimens of both sexes, all ages and varieties, and of wide geographical distribution.
In 1821 he joined the firm of his father-in-law, Matthew Carey, who was engaged in the largest publishing business in the United States. In 1827 he began a series of memoirs on new forms of fresh-water and land shells, which have been continued to the present time. These were published in the "Transactions of the Philosophical Society," vols. iii. to x., and in the " Journal of the Academy of Natural Sciences," vols. iii. to vi., and separately under the title of " Observations on the Genus Unio," etc. (13 vols. 4to, 1827 et seq.; the 13th volume being prepared for press in 1873). In 1832 he visited Europe, and in 1833 published "Contributions to Geology," consisting of descriptions of 228 species of tertiary fossils from Alabama, illustrated with great exactness in colors. He retired from business in 1851, and his time has since been devoted to his favorite scientific pursuits. In all he has read 157 original papers to learned societies. In 1852 he made a second visit to Europe, and soon after his return published, in large folio, with colored plates, " Fossil Footmarks in the Red Sandstones of Pottsville," intended to illustrate the remarkable discovery made by himself of saurian footprints in the red sandstone 700 ft. below the conglomerate of the coal formation at Pottsville, and named by him sauropus pri-maevus. This discovery was of great interest, as it had been believed until within a few years that no "air-breathing animal" had existed even so low as the coal measures.
In another memoir he described the bones and teeth of a saurian from the new red sandstones of Pennsylvania. These constituted the first bones and teeth observed in this formation in the United States, and the animal was named by him clepsysaurus Pennsylvanicus. These discoveries were followed by others which have been communicated to the academy of natural sciences. Mr. Lea has contemplated the publication of a large work on the unionidae of the United States, which is to be a complete monograph of the genera and species of that family. His memoirs published within the last 4G years are preparatory to this object. He was elected a member of the American philosophical society in 1828, and subsequently of the zoological society of London, the Linnaean society of Bordeaux, the imperial society of natural history of Moscow, honorary member of the Asiatic society of Bengal, etc. In December, 1858, he was elected president of the academy of natural sciences of Philadelphia. Among his works, besides those already mentioned, are " Description of a New Genus of the Family Melaniana" (8vo, 1851), and " Synopsis of the Family of Naiades" (4th ed. enlarged, 4to, 1870).
II. Thomas Gibson, an American botanist, brother of the preceding, born in Wilmington, Del., Dec. 14, 1785, died in Waynesville, O., Sept. 25, 1844. He was engaged in mercantile affairs until his 43d year, when he retired from business and devoted himself to botany. He left an extensive herbarium with the synonomy and description of many new species, and an unfinished catalogue. A "Catalogue of Plants, Native and Naturalized, collected in the Vicinity of Cincinnati, 0." (8vo, Philadelphia, 1849), was prepared from his papers by Mr. W. S. Sullivant.
III. Matthew Carey, an American chemist, son of Isaac, born in Philadelphia in 1823. He studied chemistry in the laboratory of Prof. James Booth, and directed his attention to special branches of the science. His first published papers, in the "American Journal of Science," were a series of analyses of the coals from the various mines of Pennsylvania and Maryland. These were followed by papers on picric acid and its salts; on nitrate and nitrite of ethyl; on the ethyl and methyl ammonias, with their separation and reactions; on the germination and growth of seeds; on the platinum metals, with improved methods of separating them, etc. He is, however, best known by his papers on photographic chemistry. He made a special study of the chemical effects of light, more particularly on the silver haloids, upon which subject he published papers in various scientific periodicals. His "Manual of Photography " (Philadelphia, 1868; 2d ed., 1871) is a work of standard authority among photographers.
IV. Henry Charles, an American author, brother of the preceding, born in Philadelphia, Sept. 19, 1825. He entered into business at the age of 17, and has been for many years at the head of a large publishing house in Philadelphia. During the civil war he organized the system of municipal bounties to encourage volunteering, and wrote much for periodicals. Since that time he has taken an active part in urging many important measures of political reform. A paper written by him at the age of 14, on the salts of manganese, was published in Silliman's " Journal." He also published papers on fossil and recent con-chology, and wrote largely on literary and critical subjects. About 1857 he directed his special attention to the study of European mediaeval history, and has published "Superstition and Force: Essays on the Wager of Law, the Wager of Battle, the Ordeal, and Torture " (1866; enlarged ed., 1870); " Historical Sketch of Sacerdotal Celibacy in the Christian Church " (1867); and " Studies in Church History: the Rise of the Temporal Power, Benefit of Clergy, and Excommunication" (1869). He is now (1874) engaged in collecting material for a history of the inquisition.