judge by that part of the column which is actually exposed to view, there is no indication whatever of a steady progression from lower, to higher, degrees of organization, and it takes all the imperturbable idealism of a scientific doctrinaire to discern in such random, abrupt, and unrelated “origins” any evidence of what Blackwelder styles “a slow but steady increase in complexity of structure and in function.” (_Science_, Jan. 27, 1922, p. 90.) But, while the permanence of phyletic types excludes progress, that of generic and specific types excludes change, and hence it is in the latter phenomenon, especially, that the theory of transformism encounters a formidable difficulty. Palæobotany furnishes numerous examples of the persistence of unchanged plant forms. Ferns identical with the modern genus _Marattia_ occur in rocks of the Palæozoic group. Cycads indistinguishable from the extant genera _Zamia_ and _Cycas_ are found in strata belonging to the Triassic system, etc., etc. The same is true of animal types. In all the phyla some genera and even species have persisted unchanged from the oldest strata down to the present day. Among the Protozoa, for example, we have the genus _Globigerina_ (one of the Foraminifera), some modern species of which are identical with those found in the Cretaceous. To quote the words of the Protozoologist, Charles A. Kofoid: “The Protozoa are found in the oldest fossiliferous rocks and the genera of _Radiolaria_ therein conform rather closely to genera living today, while the fossil _Dinoflagellata_ of the flints of Delitzsch are scarcely distinguishable from species living in the modern seas. The striking similarities of the most ancient fossil Protozoa to recent ones afford some ground for the inference that the Protozoa living today differ but little from those when life was young.” (_Science_, April 6, 1923, p. 397.)