quest of Dr. Gray, Dr. Lea went over the collection of the Unionidæ, arranged and named them correctly, and added some new species from the United States. He called, in Paris, on Baron Ferussac, the eminent student of terrestrial and fluviatile mollusca, who was then engaged in preparing his great work on the Unionidæ. During the conversation the baron "complimented Dr. Lea by saying that he could not go on with his work until he (Dr. Lea) had finished his memoirs." Dr. Lea afterward spent several hours in going over the baron's collections, which contained Unionidæ from Brazil, Syria, Turkey, and Egypt, and rearranging it, cutting down the species and forming numerous synonyms. Afterward, he met Blainville, Ferussac, and others at the Jardin des Plantes, to arrange and name all the Unionidæ of the collection there, to which he added fourteen species. From Studer, the elder, in Berne, he received the last copy in the author's possession of his work on the land and fresh-water shells of Switzerland, and compliments on the papers he had himself written. At Paris, again, he examined the Unionidæ in the Duc de Rivoli's collection, which contained all those of Lamarck, and was thereby able to identify all of Lamarck's species in his subsequent memoir. Calling on M. Gay by invitation, he was shown all the mollusca which that naturalist had collected in his travels, and was invited to select a specimen of each. Thus he found the most eminent naturalists everywhere, on the strength of the few papers he had published on American mollusca, ready to welcome him as one of themselves, and to receive instruction from him. Their general message to him was to go on with the investigations he had begun, with the assurance that no naturalist in America or Europe had the advantages that he possessed.
On returning home in November, 1832, he found that he had been anticipated in a work he should have done on the Tertiary shells of Alabama, but, having specimens of the species in his cabinet, he prepared a paper, "Contributions to Geology," which he presented to the Academy of Natural Sciences in August, 1833. It contained two hundred and twenty-one species. His "Synopsis of the Family Naïades," published in 1836, and afterward supplemented and expanded, is said to have settled satisfactorily to most conchologists the synonymy of the species. On receiving it, Prince Charles Bonaparte expressed a desire to see all parts of zoölogy treated in the same manner. In 1849 Dr. Lea presented a paper on the foot-marks of the reptile Sauropus primævus, found by him in the red shales at Pottsville, Pennsylvania, seventeen hundred feet below the conglomerate, which was of interest on account of the discussion it excited as to the age of the fossil. The foot-prints were assigned to the old red sandstone, while Professor Agassiz had declared that he did not believe that any air-breathing animals had existed before the new red sandstone. The discussion was kept up for several years, in the course of which Dr. Lea reiterated and maintained his position that the fossil was what he
