LEO LESQUEREUX. 4 6l 



mosses. At the close of the year 1849, under the advice and 

 with the co-operation of Mr. Sullivant, he made a tour of ex- 

 ploration among the mountains of the Southern States, for the 

 collection of plant specimens, and secured a great variety of 

 plants, which found a ready sale among students of botany. 

 He was particularly successful in the collection of mosses. 

 The preparation of the specimens, their determination and 

 distribution, gave him employment for two years, and resulted 

 in one of the most valuable contributions to American bry- 

 ology the Musci Americani Exsiccati, by W. S. Sullivant and 

 L. Lesquereux. The expense of preparation and publication 

 of this work was defrayed by Mr. Sullivant, who, taking only 

 a few copies for presentation, allowed his colleague the benefit 

 of the sales of the rest. Using that author's library and her- 

 barium Lesquereux lent most valuable assistance to the prepa- 

 ration of Mr. Sullivant's works on the mosses of the Wilkes 

 South Pacific Exploring Expedition, Whipple's Pacific Rail- 

 road Exploration, and the Icones Muscorum. 



Sullivant had collected materials for a complete account 

 of the North American moss flora, which he hoped to publish. 

 After his death, at the urgent request of Dr. Asa Gray, Les- 

 quereux undertook to complete the task. A large part of the 

 work was done when, in 1869, his sight became impaired, and 

 Prof. Thomas P. James, of Cambridge, was enlisted in this 

 labour. He made the microscopical examinations that were 

 still to be done, but his death caused another delay, and it was 

 not till 1884 that the Manual of North American Mosses was 

 finally issued. 



The publication of Brongniart's Prodrome, and the com- 

 mencement of the Histoire des Vdgtfaux Fossils, in 1828, laid 

 the solid basis upon which the science of paleobotany has been 

 erected. Lesquereux began to write on this subject in 1845, 

 and his studies in America have been directed especially in 

 the line of fossil botany. His most valuable researches, be- 

 ginning in 1850, lay in the study of the coal formations of 

 Ohio, Pennsylvania, Illinois, Kentucky, and Arkansas, and his 

 reports appear in the geological surveys of all these States. 

 He had conceived that his theory of the formation of peat 

 could be extended to the coal, and this proved to be the case. 

 Particularly important are his studies of the coal flora of Penn- 

 sylvania, published in the report of H. D. Rogers in 1858, 



