120 DR. J. ^V. HESLOP HARRISON ON 



of four miles crowds upon crowds of aliens, casuals, and 

 stragglers ; some of these are rare and some common, but 

 all are of interest. At the Port Clarence end these are the 

 usual Linaria vulgaris, Reseda lutea, R. luteola, Artemisia 

 vulgaris, A. absinthium and Senecio viscosus, but further along 

 a better class of plants appears and with them two or three 

 quite unusual performers in the rule of casual. These 

 gradually yield, as we digress to the abandoned section, to a 

 settled type of vegetation reminiscent of the earlier days 

 suggested by such ancient Greatham specialities as Erigeron 

 acris. Omitting plants everywhere plentiful on such land in 

 Durham, but including others common in normal habitats 

 with us, the following plants are present : — 



Diplotaxis tenuifolia Hieracium pilosella 



Lepidium draba (rare el.sewliere in the district) 



Linum perenne Aster linosyris 



Viola S3'lvestris Erigeron acris 



Priimila veris Artemisia campeslris 



Ulex europaeus Verbascum nigrum 



Trifolium ochroleucum Euphorbia exigua, var. retusa 



Carduus nutans Bromus arvensis 



Of cryptogams, a thick carpet of the lichen Peltigera ca/ii/ia, 

 with the moss Funaria hygrophila (which, whatever may be 

 its reputation, does not abound with us), and several species of 

 Brytim provide a seedbed for the Erigeron. 



v.— THE SALTMARSHES. 



Greatham Marsh. 



Greatham Marsh, although now but a shadow of its former 

 self, consists of two fairly extensive tracts bordering Greatham 

 Fleet or Creek about three miles from the open sea ; beyond 

 these limits all possible extension by tidal action is prevented 

 by the old earthwall. Eastward, it terminates at the smaller 

 transverse wall linking up these walls with the tremendously 

 powerful slag barrier just above the iron bridge. To the west, 

 its southern half extends along the Creek until the stream 

 takes its last sudden bend to the north-west, whilst the 

 northern section reaches a point to the south of Cerebos Salt 



