BOTANY The flora of east Gloucestershire is but imperfectly known, so that Berkshire possesses a very large number of species which are not recorded for it. Several of the Berkshire species are not likely to occur in Gloucestershire, nor are we at all likely to have as native plants many of the above species. The geological map of Berkshire shows that the outcrop of the several formations appears as a series of approximately parallel strips crossing the county from west to east, and the dip of the beds is to the south ; so that in travelling from north to south we pass continually on to more recent beds. For botanical purposes subdivisions of the county are essential, and following the practice adopted in the floras of the bordering counties, including my own Flora of Berkshire, these divisions are based, not upon soils or geological formations, but upon river drainage, as by many authorities the latter leads to the most valuable scientific results. Much however is said in favour of choosing divisions based upon the geological formations, but the extent to which these are obscured by surface deposits negatives to a great extent its value, the influence of the surface soil being infinitely more powerful than the bed rock far below. We shall find however that the divisions based upon the river drainage in such a small area as the one we are treating of is by no means perfectly satisfactory for several reasons, among which may be named the difficulty in suggesting boundaries when the gradient is so small as that which occurs in some places, while the fact that some of our streams run transversely to the geological formations, and not unfre- quently cut through several beds of extremely different character, also give results which may perplex the student of phyto-geography. In passing we may mention that the oldest and most northern geological formation represented in the county is that of the Oxford Clay, which, as will be seen from the map, occurs on a narrow strip of low-lying land, chiefly pasture, a mile or two across, which borders the southern bank of the Thames from Lechlade to Botley, and it also stretches in the west from Lechlade to Coleshill and on the east as far south as to Iffley. It offers no exceptional plant vegetation, but the graceful sedge (Carex pendula) is very abundant on it in Wytham Woods, the Cyperus grass (Scirpus sylvaticus) is plentiful in one locality, and the horsetail (Equisetum maximum) is also frequent at its junction with the coralline oolite in several localities. Plants which are exceptionally common on it are a groundsel (Senecio erucifolius] , the teasel (Dipsacus syfoesfris), the hard rush (Juncus glaucus) the ox tongue (Picris Echioides), the knapweed (Centaurea nigrd) and the fleabane (Pulicana dysenterica), but these also reappear on the other impervious formations. Next in order are the Corallian Beds, which afford a valuable soil, sandy or rubbly, but always porous and warm according as sand or lime- stone forms the bed rock. On the south these beds can be traced trom Shrivenham and Faringdon eastwards in a belt about 3 miles wide as far as Abingdon. At Wytham they form a picturesque outlier which rises to a height of 538 feet, and give a home, the most northerly in the i 4i 6
