And yet with all the alleged vicissitudes of the continents during the millions of years since the Cretaceous age, there is so far as I am aware not a trace of either the chalk or the sponges in any of the "subsequent" rocks. Pieces of Cretaceous rock are of course found thus sporadically as boulders, but there is no natural deposit of this kind. But in the light of these modern discoveries why is not the Chalk of "the white dear cliffs of Dover," full of modern living species as we now know it to be, just as "recent" a deposit as the "late" Tertiaries or the Pleistocene? Another good illustration of the absurdity of the present arrangement of the rocks is found in the Echinoderms--crinoids, star-fishes, sea-urchins, etc. Of the latter Prof. A. Agassiz found in the deep waters of the West Indies, four genera of Echinids or sea-urchins of the "later Tertiary," =but 24 genera of the "early" Tertiary, 10 of the Cretaceous, and 5 of the Jurassic=.[48] But far from being uncommon we know that similar discoveries have been in almost constant progress during the last half century. And were it not that "zoological students are," as Zittel says, "too actively engaged and keenly interested in building up new observations to attempt to spell through the arbitrary palaeontological conclusions" found in the "dead weight of stratigraphical-palaeontological literature," there is no telling what hosts of similar facts might not be pointed to regarding the forms found in all the "older" rocks.