Botany. 145 



populated seaside localities. The foreshore nuisance in 

 Belfast I.ough seems largely due to the decaying Sea-lettuce 

 left exposed at low tide. How far the presence of these 

 weeds is an indication of putrefying animal matter present 

 is not settled, but there is some evidence which tends to 

 show that an increase of such weeds is directly proportional 

 to the amount of sewage matter present. 



Olive-brown Seaweeds (Pheophycete). — In this group, 

 including the common Oarweeds and larger species of 

 wracks, there occur many typical genera. Many of the 

 smaller, less conspicuous forms are also well represented. 

 Of the rarer of these less familiar types we note the following : 

 Phlu'spora brachiata (Harv.) Born., found at the The Gobbins 

 attached to Fucus serratus. Striaria attennata grows in 

 Belfast Lough and Strangford Lough. The genus Streb- 

 lotieina grows on other Algje; the host-plants are either green, 

 red, or olive-brown seaweeds. It exists as fine tufts of 

 delicate filaments, which pierce the tissues of the host, form- 

 ing intra cortical threads, and in this way infecting other 

 parts of the host-plant. Streblonema Areschoui^^ii Crn. grows 

 as a little rounded cushion, the size of a large pin's head, on 

 the surface of the thongs of the Jkitton-wrack, Hii/ianthaHa 

 lorea, at Murlough Bay, Co. Antrim. Of the genus Ecto- 

 carpus^ many beautiful species are known from these shores. 

 Ectocarpiis Hinksice, first discovered at Ballycastle in 1840, 

 is found also at Murlough. E. penicillatus C. Ag. grows on 

 Alaria esculenta, and E. fasciculatiis f. draperjialciioides Crn. 

 are found at Murlough. Arthrocladia villosa, a southern 

 form, is recorded from Carrickfergus by McCalla, and from 

 the County Down coast by Mrs. Catty : more recently it has 

 been dredged in these localities. Petrospongiutn Berkeleyi 

 is found at Murlough and the Giant's Causeway on rocks 

 exposed to the surf at low water. 



Red Seaweeds. — Many beautiful forms of this group 

 ( Rhodophycece) are found on these coasts. Goniotrichum 

 elegans Le Jol. was dredged by Mr. Thompson in Strangford 

 Lough. Porphyra leiicosticta and P. linearis are found at 

 Larne and Murlough. JVildmannia miniata, Murlough 

 Bay. Diploderma amplissi7?ium, Cushendall. Pliyllophora 

 Traillii, Tor Head. Many species of Nitophyllum are repre- 

 I 



