A BOTANICAL TOUR. 119 



mits of the rocks, suggesting the idea that a great portion of the flora of the west 

 of England may have had its origin from hence. Pukton has remarked inci- 

 dentally, but without founding any conclusion upon it, that many plants of rare 

 occurrence in the midland counties, are common in South Wales, and I have 

 found this observation to be, in a great measure, correct. Now if, as is generally 

 understood, the red sand-stone, and the strata above it, in the order of depo- 

 sition, still lay beneath the waters at a period posterior to the elevation of these 

 carboniferous rocks, they must have derived their vegetation when uncovered, 

 from the immigrations of the plants congregated upon this pre-existing dry land. 

 Whether, in fact, the very plants upon the rocks here are really indigenous, or 

 derived from other countries, it may be now indeed difficult at once to say. The 

 origin of plants is a question still undecided, but whether one or many centuries 

 of creation are admitted as the most correct theory, it would be unphilosophical 

 to assume the gratuitous creation of new plants for any newly immerged land, 

 so long as other lands can be proved to have been in existence, from whence vege- 

 tation could proceed to clothe the bed of the retiring ocean. For as an old wall 

 left to the elements is attacked and enveloped by the progeny of the plants around 

 it brought by the winds and rains, so in like manner must former newly emerged 

 portions of the earth's surface have received their vegetable colonies from older 

 and pre-existing strata of land. All that is required to constitute fit habitats for 

 nine-tenths of the phenogamous species in the British Flora, is the sandy sea- 

 shore, salt-marshes, fresh-water pools and bogs, and limestone eminences, all 

 which occur here within a compass of three miles, taking Swansea as the centre. 

 I conclude, then, that the great majority of British plants existed on these lime- 

 stone hills, while a considerable proportion of England was covered by the sea. 

 They must, however, have sprung up even here subsequent to the destruction 

 of the plants of the coal formation, but whether derived from extraneous sources, 

 or created here ab origine, it is difficult, and perhaps impossible, at present to 

 decide. The following plants were all gathered by me upon the carboniferous 

 limestone, between the Mumbles, Caswell Bay, and Oystermouth : — 



*Arabis hirsuta. — -Abundant on the wails of Oystermouth Castle, and at other 

 places in the vicinity. Also on the cliffs at Caswell Bay. 



*Arabis turrita. — In the chamber over the Barbican, Oystermouth Castle. 



*Cochlearia danica. — In several of the deserted uncovered apartments of Oys- 

 termouth Castle. 



*Lepidium Smithii. — Plentiful about Swansea. 



*Brassica campestris. — Among rubbish near the sea. 



Helianthemum canum. — On the rocks opposite the Mumbles Lighthouse, on 

 the mainland. 



Hypericum humifmum. — On the hills towards Caswell Bay. 



