HENRY SHALER WILLIAMS 699 
to be found in their own dooryards rather than to think that any 
problem worth solution must be sought for in distant parts of the 
earth. His exceedingly careful investigation of the geological 
section at Ithaca, with the careful collection of fossils from bed to 
bed and the study of their associations in faunas and faunules, 
and his observations upon the geologic range of species and their 
recurrence at different horizons in the section really brought to 
the attention of students of fossils a new field for research and new 
problems whose relations to the problems of the stratigraphic 
geologist were much more intimate than the mere search for and 
naming of new fossil species. 
For a number of years he continued his studies of the fossil 
faunas of the Devonian in central New York, making careful com- 
parisons between the faunal succession as he had found it at Ithaca 
and the succession in other sections farther west, which represented 
the same time interval. The results of these very careful observa- 
tions upon the faunas and their stratigraphic relations led to his 
proposal of the doctrine of “shifting faunas”? within the limits of: 
a single basin, the movements of the various faunal associations 
being governed by changing environmental conditions. All these 
studies led him more and more to the consideration in its broader 
aspects of the succession of life forms upon the earth, and directed 
his studies into the field of organic evolution as exemplified by the 
actual geological history of organisms. 
The unique character of Professor Williams’ investigations of the 
Devonian faunas of central New York early called attention to his 
studies and led to his selection as director of the Devonian work of 
the United States Geological Survey, to which was also added the 
direction of the work upon the Carboniferous. His survey con- 
nection made it possible for him to extend his studies into broader 
fields but did not lead to the severing of his university ties. Among 
other problems his survey work led him to the study of the Devonian 
faunas of Maine, and his latest contributions to the literature of 
paleontology have had to do with the Devonian and Silurian fossils 
of that state. 
In 1892 Professor Williams left Cornell University to become 
Sillman professor of geology in Yale University, where he succeeded 
