TKANSACTIONS OF SECTION D. 683 



In none of the species, except the vine to which I have referred, which Dr. 

 Schweinfurth has discovered, and of which he has made a careful study, has he 

 heen able to detect any peculiarities in the living plants which are absent in those 

 obtained from the tombs. 



Before passing from these Egyptian plants I would draw attention to the quality 

 of the cereals. They are good specimens of the cereals still cultivated. This ob- 

 servation is true also of the crdtivated grains which I have examined, belonging to 

 prehistoric times. The wheat found in the purely British portion of the ancient 

 village explored by General Pitt-Eivers is equal to the average of wheat culti- 

 vated at the present day. This is the more remarkable, because the two samples- 

 from the later Romano-British period obtained by General Pitt-Rivers are very 

 much smaller, though they are not unlike the small hard grains of wheat still culti- 

 vated on thin chalk soils. The wheat-grains from lake dwellings in Switzerland, for 

 which I am indebted to J. T. Lee, Esq., F.G.S., are fair samples. My colleague, 

 Mr. W. Fawcett, has recently brought me from America grains of maize from the 

 prehistoric mounds in the valley of the Mississippi, and from the tombs of the lucas 

 of Peru, which represent also fair samples of this great food-substance of the New 

 World. The early peoples of both worlds had then under cultivation productive 

 varieties of these important food-plants, and it is remarkable that in our own coimtiy, 

 with all the appliances of scientific cultivation and intelligent farming, we have not 

 been able to appreciably surpass the grains which were harvested by our rude 

 ancestors of two thousand years ago. 



In taking a further step into the past, and tracing the remains of existing 

 species of plants preserved in the strata of the earth's crust, we must necessarily 

 leave behind all certain chronology. Without an intelligent observer and recorder 

 there can be no definite determination of time. We can only speculate as to the 

 period required for efifecting the changes represented by the various deposits. 



The peat-bogs are composed entirely of plant-remains belonging to the floras 

 existing in the regions where they occur. They are mainly surface accimiulations 

 still being formed and going back to an unknown antiquity. They are subsequent 

 to the last changes in the surface of the country, and represent the physical 

 conditions still prevailing. 



The period of great cold during which arctic ice extended far into temperate 

 regions was not favourable to vegetable life. But in some localities we have 

 stratified clays with plant-remains later than the Glacial Epoch, yet indicating 

 that the great cold had not then entirely disappeared. In the lacustrine beds at 

 Holdemess is found a small birch {Betvla nana, L.), now limited in Great Britain 

 to some of the mountains of Scotland, but found in the Arctic regions of the 

 Old and New World and on Alpine districts in Europe, and with it Prunus 

 Padus, L., Quercus Rohur, L,, Corylus Avellann, L., Alnus glutinosa, L., and 

 Pinus syhesti'is, L. In the white clay beds at Bovey Tracey of the same age there 

 occur the leaves of Arctostaphylos Uva-Ursi, L., three species of willow, viz., 

 Salix cinerea, L., S. myrtilloides, L., and S. polaris, VVahl., and in addition to 

 our alpine Betula nana, L., the more familiar B. alba, L. In beds of the same 

 age in Sweden, Nathorst has found the leaves of Th-yas octopetala, L., and Salix 

 herbacea, L., this being associated with S. polaris, Wahl. Two of these plants 

 have been lost to oui- flora from the change of climate that has taken place, viz., 

 Salix myrtilloides, L., and S. polaris, Wahl. ; and Betula nana, L., has retreated to 

 the mountains of Scotland. Three others {Dryas octopetala, L., ArctostapJiylos 

 Uva-Ursi, L., and Salix herbacea, L.) have withdrawn to the mountains of 

 northern England, Wales, and Scotland, while the remainder are still found 

 scattered over the country. Notwithstanding the diverse physical conditions to 

 which these plants have been subjected, the remains preserved in these beds 

 present no characters by which they can be distinguished from the living repre- 

 sentatives of the species. 



We meet with no further materials for careful comparison with existing species 

 until we get beyond the great period of intense cold which immediately preceded 

 the present order of things. The Glacial Epoch includes four periods during which 

 the cold was intense, separated by intervals of somewhat higher temperature which 



