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LEA, ISAAC (b. Wilmington, Delaware, 4 March
1792; d. Philadelphia, Pennsylvania, 8 December
1886), malacology.
The fifth son of James Lea, a Quaker merchant
of Wilmington, Isaac attended the local academy with
the idea of becoming a physician; but at the age of
fifteen he went to work in the Philadelphia mercantile
business of his brother John, who eventually made
him a partner. In Philadelphia, Lea formed a lifelong
friendship with Lardner Vanuxem, with whom he
roamed the countryside collecting minerals, rocks, and
fossils. They were both elected to the Academy of
Natural Sciences of Philadelphia in 1815; and in 1818
Lea published in its Journal his first scientific paper,
“An Account of the Minerals at Present Known to
Exist in the Vicinity of Philadelphia.” The study of
geology led to the study of shells, and Lea spent
several years studying the collections of freshwater
mollusks that Major Stephen Long had sent to the
Academy from the Ohio River and that his brother
Thomas Lea had gathered for him near Cincinnati.
In 1827 he published, in Transactions of the American
Philosophical Society, “A Description of Six New
Species of the Genus Unio.” Thereafter he devoted
most of his scientific attention to “this truly seducing
branch of Nat: Hist:.” His Contributions to Geology
(Philadelphia, 1833), a descriptive catalogue principally
of specimens of the Tertiary formations at
Claiborne, Alabama, firmly established his reputation.
Its text was distinguished by care and judgment; and
its typography and illustrations, Roderick Murchison
told the author, had “quite the stamp of being issued
by one of the best workshops of Europe.”
The subject was well chosen, for although mollusks
abounded in American rivers, scarcely anyone had
searched for them there. An acute and accurate
observer, during a long lifetime Lea collected, identified,
and described, chiefly in papers to the Academy
of Natural Sciences and the American Philosophical
Society, 1,842 species of some fifty genera of freshwater
and terrestrial mollusks. “I sometimes fear I
take up too much room in the Society's Transactions,”
he once half-apologized, “but it is a great matter to
have new objects of Natural History well illustrated—it
saves hundreds of mistakes which in time might
otherwise occur.” In addition to shells, Lea figured
the embryonic forms of thirty-eight species of Unio
and described the soft parts of another 234. His
Synopsis of the Family of Naïades (Philadelphia-London,
1836; 4th ed. 1870) classified the synonymy
of the Unionidae, until then in great confusion. He
also investigated physiological questions, such as
mollusks' sensitivity to light and differences due to
sex. Lea ordered 250 reprints of each paper, bound
them up from time to time with title page and introduction
as Observations on the Genus Unio (13 vols.,
1827-1874), and presented them to institutions and
individuals. “Your intelligent perseverance with
consummate skill & taste have reared a brilliant
monument in this part of conchology,” the elder
Silliman told him in 1860 in acknowledging one of
these volumes. Lea's bibliography, compiled in 1876,
contained 279 titles.
Lea's personal collection was steadily augmented
by gifts from other naturalists—among them Jeffries
Wyman, Charles M. Wheatley, Bishop Stephen
Elliott, Gerard Troost, John LeConte, and Dr. John
Kirk, who accompanied Livingstone to Lake Nyassa.
After seeing Lea's cabinet in 1846, Agassiz declared
“that all which European naturalists have written on
this subject must be revised.” Captain Frederick
Marryat pronounced it “certainly the most interesting
[museum] I saw in the States” and a principal reason
why Philadelphia, not Boston, must be considered
“the most scientific city in the Union.” In his later
years Lea turned to the study of crystals and is said to
have been the first in America to engage in microscopic
mineralogy.