452 BUIJ^ETm lO'J, UNITED STATES NATIONAL MUSEUM. 



1874 Leo. Lesquereux was commissioned to repeat and extend this 

 investigation from year to year. In 1880 the first and second parts, 

 and in 1884 the third and last part of his Coal Flora were published, 

 in 980 pages, octavo, of text and 111 double-page plates of figures. 



In the final report of 1858, Professor Rogers gave 20 quarto 

 pages (vol. 2, pp. 815 to 834) to a chapter on organic remains of the 

 Paleozoic strata of Pennsylvania, with 90 good woodcut figures of 

 algae and molluslis, characteristic of the 13 formations; an average 

 of seven species to each formation. The contrast between this and 

 the numerous volumes of text and plates published by the New York 

 Geological Survey was sufficiently striliing, and produced a general 

 impression upon the minds of paleontologists that while the thin 

 northern outcrops of Silurian and Devonian rocks in New York and 

 Canada were extraordinarily rich in organic forms, their vastly 

 thicker southern outcrops in middle Pennsylvania were extraordi- 

 narily barren of remains. But in fact all the energies of the Penn- 

 sjdvania survey were insufficient to cope with its structural and eco- 

 nomical problems; and it was with the sincerest satisfaction and 

 without a trace of jealousy that the Pennsylvania geologists saw 

 themselves in good measure exonerated from the additional task of 

 paleontological field work, feeling how completely it was being 

 done for them by the alile geologists and the great paleontologist of 

 tlie State of New York, whose volumes were as available as if they 

 had been based on collections made in Pennsylvania. 



In a purely scientific sense this tacit mutual arrangement is now 

 seen to have been a little unfortunate, as it fixed on American 

 paleontology certain dogmatic determinations of time-order, which 

 a thorough scrutiny of the southern outcrop belt carried on /)«H 

 passu with that of the northern outcrops, would have modified. But, 

 after all, no real harm was done: and at all events no other course 

 was left open to the earlier surveys of Pennsylvania. Even when 

 the survey was reorganized in 1874, and for some years afterwards 

 the same arrangement had to be renewed; although an attempt 

 was made to handle the collections as they came in to headquarters, 

 and a paleontological assistant was commissioned as curator of the 

 museum. But his attention was soon diverted to the urgent study 

 of the mj^sterious azoic belt in the southeastern corner of the State; 

 while the whole force of the survey had to be expended upon a re- 

 vision of the structure and economics of the counties. The survey, 

 if not practical, would not have been continued by successive legis- 

 latures. Paleontology was again sacrificed to structural and chemi- 

 cal geology, to mapping and sectioning, and outcrop tracing. 



The only paleontological work done from 1875 to 1880 was that of 

 Prof. J. J. Stevenson and Prof. I. C. White along the West Virginia, 



