370 THE JOURNAL OF BOTANY 



The only previous record of this species in Britain is from the 

 Isle of Cumbrae (Batters in Grevillea, vol. xxi. p. 21). The present 

 specimens, collected at Swanage in April of this year, were growing 

 on Bhodymenia palmata, and mixed with Hecatonema diffusum. 

 The plants were of small size, and of the type described by 

 Eosenvinge on the same host. 



Hecatonema globosum is to be found in most of the recent 

 works which attempt to give a complete list of the algae occurring 

 in the various countries of Europe, and, as will be seen from the 

 citations above, it has been placed in five different genera. Many 

 writers have remarked on its variability, and also on the possibility 

 of more than one species being included under that name. In 

 Eeinke's original plant the upright filaments are of considerable 

 length, consisting of 10-14 cells, the sporangia being produced on 

 the ends of the ultimate branches (vide Atlas, tab. 16), whereas in 

 the form described by Eosenvinge on Bhodymenia palmata (L c. p. 86, 

 f. 20) the filaments are shorter and less branched, the sporangia 

 being borne on short stalks consisting of 1-3 cells. Jonsson also 

 (Mar. Alg. of Iceland. Bot. Tidskrift, vol. xxv. 1903, p. 147) states 

 that he found a form growing on Bhodymenia palmata " precisely 

 resembling Eosenvinge's fig. 20, with erect filaments branched or 

 unbranched, and the sporangia stalked or sessile.' ' 



The shortening of the branches above referred to brings about 

 a marked difference in the general form of the plant, the typical 

 form producing minute balls (as indicated by the specific name), 

 whilst the form on Bhodymenia is flattened, and bears a close 

 resemblance to a Myrionema. The present gathering represents 

 the third time this form has been recorded ; the records are from 

 three different countries, and in each case the plant was growing 

 on Bhodymenia palmata. For these reasons it has been thought 

 advisable to separate the plant, and to regard it as a distinct 



A typo differt ramis erectis 



variety to be characterized as follows : 



brevioribus parum ramosis, sporangiis sessilibus aut breve pedi- 

 cellatis. Bami erecti circa 100-150 /* longi, simplices vel semei 

 ramosi. Sporangia terminalia aut lateralia, sessilia vel pedicello 

 1-3 articulato suffulta. 



With regard to the systematic position, the genus to which the 

 plant was assigned by Batters seems to be the most suitable. 

 Hecatonema, as remarked by Sauvageau, possesses the upright 

 growth of an Ectocarpus, and the basal disk of a Myrionema. The 

 typical form of the present plant agrees with Hecatonema in com- 

 bining these characters, though it differs somewhat in the fact 

 that not only some but all of the thallus cells give rise to upright 

 growth. 



Hecatonema diffusum Kylin, Algenflora der Schwedischen 



Westkiiste, 1907, p. 39, fig. 10. 



On Bhodymenia palmata C 

 to Britain. 



To this species the writer has referred an alga found on Bhody- 

 menia, the specimens agreeing in all respects with those described 



New 



