304 FLOEA OF PLYMOUTH SOUND 



Rhodymenia, Pijlaiella littoralis, Scytosijyhon loiiientarius, Bryopsis 

 jjluinosa. 



Middle Fort (behind Breakwater). 



Examination of the inter-tidal and extra-tidal surface of this fort 

 brought to light Spondylothamnion multifida (very fine plants), several 

 species of Callithamnioii, including C. thuyoideutn, C. seirospermum, 

 C. gracillimum, Antithamnion plumula, jS, species of Nitophyllum, 

 Gigartina, Rhodymenia, Delesseria, Chylocladia, Porphyra, Desma- 

 restia, Ectocarpus, Ulva, &c. 



The Buoys. 



Examination of the buoys, with which Plymouth waters abound, 

 serves to give one some idea of the migrations of marine plants. 

 It should be remembered that all the buoys are thoroughly cleaned 

 and repainted twice a year (before and after winter — end of Septem- 

 ber, beginning of April). They might be used, coated with different 

 substances, for experiments having as their object the discovery of 

 the best weed-growing preventatives as applied to ships' bottoms. 

 The weeds were generally healthy, in full fruit, and firmly attached. 

 Those on the White Buoy, south-south-west of Drake's Island, were 

 relatively poor and insecurely attached. 



Draystone Buoy (off Penlee Point). 



It was of interest to find plants of Rhodymenia palmata, for in 

 this species no British fruit-bearing specimen has yet been found, 

 only tetraspore-bearing forms. 



Amongst others on the buoy were Chantransia, Polysiphonia, 

 including P. Brodicsi (the tufted branches of which form nests for 

 Isopoda), Punctaria, Scytosiphon, Sphacelaria, Pctocarpus. Ulva, 

 Enteromorpha . The weeds growing on the buoys outside the Break- 

 water, mai'king the east and west channels for vessels, included those 

 found on the Draystone Buoy, and, in ?^,^i^i\i\o'[^ ,Bangia fusco -purpurea, 

 Ceramilun ruhrum, Callith amnion, Laminaria saccharina, Desmarestia 

 ligulata. The weeds on the Duke Rock Buoy were similar to those 

 on the outer buoys, but less abundant. 



Desmarestia. — With the exception of a brief notice in Eltudes 

 Phycologiques by Thuret and Bornet (p. 16) of unilocular sporangia 

 in Desmarestia viridis, no description of reproductive organs in any 

 species of Desmarestia has yet appeared. On a small plant of 

 Desmarestia ligulata I was fortunate enough to find (after examining 

 every plant of Desmarestia met with during my stay) unilocular, 



