to the microscopic examination of quartz-crystals, with drawings and descriptions of the inclusions and markings of each, so that Professor H. Rosenbusch, in his work on the subject, mentioned him as having been the first in America to enter into microscopic mineralogy. He had engaged, since his return from Europe, in other branches of natural history than conchology. The elephant folio edition of the account of the fossil foot-marks near Pottsville elicited warm commendation for the beauty of its execution and illustration. In 1858 appeared a memoir on the embryology of the Unionidæ, giving descriptions and figures of thirty-eight species. In all of his papers he described eighteen hundred and seventy-two species of mollusks of various kinds, most of which were from the United States. The series was embodied in a private edition of thirteen volumes, with three indexes, which the author distributed among men of science and learned societies. Richard Owen, acknowledging the receipt of one of the volumes, said, "They represent a kind or class of labors the most genuine and important and lasting, in the hard endeavor to gain a knowledge of Nature." Professor Haidinger, of Vienna, said, on a similar occasion, that his work would "last as long as natural science shall be cultivated by mankind. The more it is compared and studied, the more appears your power of observation, your efforts in pursuing your object, your steadiness and perseverance." M. A. Boivin wrote, "You render a great service to science in devoting your time to the classification and description of the Unio." About ten thousand individuals were displayed in Dr. Lea's cabinet of Unionidæ, so arranged that each could be separately examined, and, in many instances, with a sequence from the youngest to the oldest, so as to exhibit the aspects of growth. His other cabinets contained nearly a thousand specimens of quartz-crystals, nearly five hundred of corundum, thirty-five drawers of the mica group, and several hundred sections of lamina prepared for the microscope.
In his ninety-fourth year Dr. Lea continued in good health, with his mental and physical faculties unimpaired; and in 1884 he was able to receive and entertain about two hundred members of the British Association at his cottage at Long Branch. He was President of the Academy of Natural Sciences in Philadelphia from 1853 to 1858, and was President of the American Association in 1860. The list given in his "Bibliography" of the society honors conferred upon him numbers twenty-eight titles, and concludes with an etc. A correspondent who maintained most intimate and confidential relations with Dr. Lea for more than twenty years, furnishes a sketch of his personal character and social life, from which we quote the following words:
"Possessing a mind of great vigor and culture, he was a most genial companion to those whose tastes and sympathies accorded with his own. He was an ardent admirer of the works of Nature; and his cultivated mind enabled him to perceive many qualities and properties
