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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Pseudocetorhinus pickfordi, absent in the basal bone bed, are relatively abundant in the four overlying bone-bearing units. These differences in faunal lists and in relative proportions probably do not reflect sampling, but some major differences in ecology and evolution.

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WITHIN recent years observers working with different varieties of Nicotiana tabacum grown commercially in the United States and elsewhere have recorded the sudden appearance of occasional giant plants of abnormally high leaf number. Except in height and number of leaves, which may be increased several times above the usual number, these giant plants in general appearance do not depart widely from the varietal type from which they took their origin. The great increase in number of leaves, together with a greatly elongated main stem, is accompanied bv a period of vegetative vigor of such long duration that blossoming does not normally take place when the plants are growing in the field. In order to obtain seed from such plants, the usual practise has been to transplant the roots and stub, or even the plants entire, to the greenhouse in the fall, where vegetative vigor is resumed with the final production of normal blossoms and seed during the winter. Plants of this habit of growth have been recorded in the Sumatra, Maryland. Cuban and Connecticut Havana types of tobacco. OCCURRENCE OF GIGANTISM IN DIFFERENT VARIETIES The first published record of gigantism in tobacco appears to have been made in 1905 by Hunger (1905), working with tobacco in Sumatra in connection with an investigation of the mosaic disease. Garner (1912) mentioned a Maryland Mammoth type, the origin of which was associated with a cross between two common varieties of Marvland tobacco. Hayes and Beinhart (1914) reported the occurrence of 218