OF NORTHUMBERLAND AND DURHAM. 289 



covered rocks or sliingle at low-water mark. Not very com- 

 mon. When growing in deep tide pools it often assumes a very- 

 slender and flaccid character, somewhat similar to P. formosa^ 

 but when amongst stones in places which are left nearly dry at 

 ebb-tide, it is remarkably rigid and stunted, — N. D. 



10. P. FASTiGiATA, Gvev. Harv. Man., p. 92. Phyc. Brit., t. 



299. Atlas, PL XXVIII., fig. 127. Johnst. 

 and Cr., t. 23. 

 Conf. polymorplia. E. Bot., t. 17G4. 

 On the stems of Fucus nodosus and vesiculosus. Very com- 

 mon. — N. D. 



11. P. PARASITICA, Grev. Harv. Man., p. 92. Phyc. Brit., t. 



147. Atlas, PI. XXVIII., fig. 128. Johnst. 

 and Cr., t. 24. 

 Conf. parasitica. E. Bot., t. 1429. 



On the larger Algag, and on nullipores in deep rock pools. At 

 many places along the coast, but generally scarce. Near Seaham 

 Harbour, and among rejectamenta at Roker, Whitley, and Holy 

 Island.— (?. S. B. Whitley rocks.— ^. Foster.—^. D. 



When growing on nullipores this species does not usually 

 exceed an inch in height, but specimens which have grown on 

 other Algge sometimes attain more than twice that size. The 

 finest plants which I have gathered were found washed up on 

 Whitley sands, and generally attached to pieces of coralline or 

 to the stems of Furcellaria, Laminaria, &c. In that locality it 

 is exceedingly abundant, and during August and September 

 detached plants may be found floating in almost every pool. 

 These often form such dense tufts that they require dividing into 

 several portions before they can be laid out on paper. Some of 

 my specimens thus treated measure four inches across after 

 beins: dried. 



^>D 



12. P. BYSSOiDEs, Grev. Harv. Man., p. 92. Phyc. Brit., t. 

 284. Atlas, PI. XXX., fig. 134. Johnst. and 

 Cr., t. 25. 



