PALEOBIOGEOGRAPHY OF THE MARINE REALxM 153 



there was at least a broad climatic zonation roughly parallel to 

 present latitudinal belts in Middle and Late Jurassic time; and 

 fluctuating climatic zonation parallel to the present equator is now 

 widely accepted for the Cenozoic and late Mesozoic (see Durham, 

 1959, for a recent summary). For Paleozoic time in general the 

 question is still moot, and much additional work will be needed 

 to resolve it. 



Johannes Walther laid the basis for subsequent expansion of 

 marine paleobiogeography as a distinct empirical discipline with 

 his Einleitung in die Geologie ah historische Wissenschaft in 1893- 

 1894, and many paleontologists and geologists since Neumayr and 

 Walther have constructed paleogeographic, or, more accurately, 

 shoreline maps, utilizing various combinations of geologic and 

 paleobiologic evidence. Recent activities in marine paleobio- 

 geography are exemplified in stimulating papers by Caster (1952), 

 George (1958), Minato (1953), Ager (1956), and Davis and Elliott 

 (1957) — named in stratigraphic sequence. The summary account 

 by Davis and Elliott on the early Eocene London clay sea deserves 

 special notice, both because of the wealth of information available 

 and for the skill and balance with which these authors utilized it 

 to reconstruct the living conditions and biogeographic affinities 

 of this classic sequence. 



Growing interest in the fundamental aspects of paleobiogeog- 

 raphy is reflected by the synthetic works of the Termiers (1952, 

 1957, 1959; Wells, 1953) and by the fact that the first session of 

 the Soviet Union's All-State Paleontological Society in 1955 was 

 devoted to "Problems of paleobiogeography and biostratigraphy" 

 (Stepanov, 1957). On the western side of the Atlantic, the paleo- 

 biogeographic data are one of many ingredients of the U. S. 

 Geological Survey's program to produce a series of paleotectonic 

 maps, which will summarize the historical development from 

 Cambrian onward of sedimentation, biotal migration, and crustal 

 movement within the continental L^nited States (McKee et al., 

 1956, 1959). 



The pressing need, as in most empirical disciplines today, is for 

 a clear sequence of integrative principles that will strike more 

 directly and surely through the growing clutter of facts to the yet 



