behalf of the SOCietIes sponsoring the Treatise, the University of Kansas, and innumer-ab~e individuals benefited by the Treatise project.

2 A brief general view on the Jurassic Period (except for zoogeography) was published by the author in Encyclopaedia Britannica (1974, p. 354•360).ally effective causes, such as dynamics of dispersal, struggle for existence, climate, topographic links and barriers, salinity, water depth, currents, and supply of nutrients. Yet there is no fundamental limitation in regard to the many special facies conditions that exist in small areas, even down to the occupation of cracks in the seafloor