CENTRES OF DISPERSAL 175 



States among an almost semi -tropical fauna of colossal 

 sloths, peccaries and other southern forms that have long 

 since vanished, and which lived through it all in close proxi- 

 mity to the supposed ice-sheets and arctic climates. The great 

 majority of the Pleistocene deposits in the north indicate that 

 the country had a milder climate during the Ice Age than at 

 present, and this is particularly shown by those containing 

 plant remains. As plants are supposed to be 'more trust- 

 worthy guides than animals, as indicators of former climatic 

 conditions, I will give one more example of a Pleistocene 

 deposit from the southern States which has come to my know- 

 ledge. 



A Pleistocene deposit in north Carolina examined by Pro- 

 fessor Berry * yielded no boreal or even cool temperate 

 plants. Hence it may safely be concluded, he thinks, that 

 the temperature of the Pleistocene Period in the same latitude 

 was not lower than it is now. If anything, he says, it was 

 slightly higher. Additional facts pointing to the same general 

 conclusion are the former more northward extension of the 

 cypress (Taxodium distichum) and of Planera aquatica. That 

 these plants did not flourish during mild inter-Glacial phases 

 of tho Glacial Epoch, remarks Professor Berry, is indicated 

 by their being associated in Maryland with ice-borne boulders 

 of considerable size. 



To return once more to southern Florida, we find that what 

 we observed among plants, namely, the tropical element, is 

 likewise recognisable in the fauna. According to Dr. 

 Merriam f the semi-tropical insect fauna of southern Florida 

 comprises in all not less than a thousand species of Antillean 

 insects, half of which are beetles. 



Among the mollusks 'there are a number of Antillean genera 

 represented in southern Florida, such as Chondropoma, 

 Liguus, Cepolis, Varicella, and others spoken of by Dr. 

 Pilsbry as Mexican genera, such as Eglandina, Praticolella 

 and Drymaeus (dormani type). Dr. Pilsbry regards only the 

 last group as genuine natives of the soil. He believes that 

 their ancestors entered Florida at the close of the Miocene 



* Berry, E. W., " Pleistocene Flora of Carolina," p. 347348. 



t Merriam, C. H., " Distribution of Life in North America," p. 53. 



