29G CATALOGUE OF THE MARINE ALG^ 



One of the most variable of Britisli Alg£e, but at the same 

 time very distinct in all its forms from any other species. It 

 seems to be a very common plant on most parts of the British 

 coast, but is rare in our district. 1 know of no locality on the 

 Durham shore except that of Marsden, which, I believe, does 

 not extend beyond the limits of a very small pool. Dr. Har- 

 vey, in his excellent " Manual," enumerates twelve varieties. 

 My Marsden specimens are referable to davatum, and those from 

 Holy Island probably to aculeatum. — N. D. 



42. POLYIDES, Grev. 



1. P. ROTUNDUS; Grev. Harv. Man., p. 146. Pliyc. Brit., t. 

 95. Atlas, PL XLVL, fig. 212. Johnst. and 

 Cr., t. 60. 

 Fucus rotimdus. E. Bot., t. 1738. 

 On rocks and stones in the sea. Most frequently in pools 

 above half-tide level. — N. D. 



43. HILDENBRANDTIA, Zanard. 

 1. H. RUBRA, Meneg. Harv. Man,, p. 110. Phyc. Brit., t. 

 250. Atlas, PL XXXV., fig. 161. Johnst. and 

 Cr., vol. i., p. 169. 

 On the coast near Berwick. — Dr. Johnston. — N. 



44. PETROCELIS, Ag. 



1. P. CRUENTA, J. Ag. Johnst. and Cr., vol. i., p. 171. 



Cruoria 2)ellita. Harv. Man,, p. 151. Phyc. Brit., 

 t. 97. Atlas, PL L., fig. 227. 

 On the coast near Berwick. — Dr. Johnston. — N. 



45. CRUORIA, Fries. 



1. C. ADHJSRENs, J. Ag. J. G. Agardh, Sp. Gen. Alg., vol. ii,, 

 p, 491. Harv. in Nat. Hist. Rev., vol. iv,, p. 

 203. Johnst. and Cr., vol. i., p. 173 

 On rocks between tide marks. Newbiggen and Tynemouth. — 

 G. S. 7?.— N. 



