Ancient_and_modern_York_a_guide

MODERN YORK. 161
reaches, and in some places extends beyond, the great
summit ridge of the island. The Tees is its natural limit
on the north ; the Dun, for a great length, on the south ;
and on the east it is washed by the German Ocean. Dr.
Lister, in 1683, described the geological constitution of
the county of York in the following manner :—
1. The Wolds;—chalk, flint, pyrites, &c.
2. Blackmoor;—moors, sand-stone, &c.
3. Holderness;—boggy, turf, clay, sand, &c.
4. Western Mountains;—moors, sand-stone, coal, iron-stone, lead
ore, sand, clay, &c.
Mr. Baines, the sub-curator of the Yorkshire Philoso
phical Society, in his Flora already referred to, thus
marks the botanical divisions of Yorkshire :—
1. The north-western, or mountain limestone district.
2. The south-western, or coal district.
3. The magnesian limestone tract.
4. The great central vale.
5. The north-eastern, or Oolitic hills.
6. The chalk wolds, or south-eastern hills.
7. The district of Holderness.
8. The sea coast.
Concijologtt.
The conchologist interested in collecting the land and
fresh water shells of England, will find the vicinity of
York an interesting district. John Edward Gray, Esq.,
F.R.S., in his excellent Manual of the Land and Fresh
Water Shells of the British Islands, enumerates about
130 species: of these, no fewer than eighty are found
near and around York. The fourteen following species,
included in the above number, have been recently added
to the list :—
Keretina fluviatilis
Vertigo angustior
Paludina vivipara
Cyclas rivicola
Blthinia ventricosa
Pisidium obtusale
Cyolostoma elegaus
Pisidium pulchellum
Helix lapicida
Pisidium Henslowianum
Helix Cantiana
Unio Pictorum
Zonites purus
Unio tumidus
JHeteoroIogn.
The prevailing characteristic of the climate of York is
humidity, although the quantity of rain which falls is