"A- on the Morphology of the Fucaccc?. 33 



British Museum, I am satisfied that it does not deserve to be separated 

 from the species even as a variety. 



Agardh, in his Systeuia, p. 291, places this Alga among the Cystoseirae, 

 and in his Species Algarum he repeats this determination, and names it 

 Cystoscira axillaris. 



The genus Seirococcus was created by Greville for this plant, of which 

 it is the only known species. (Synopsis, p. 34.) 



Montagne, in Dumont D'Urville's Voyage au Pole Slid (Botauiquc, 

 vol. i., p. 86, 1845), discussing the systematic position of Seirococcus 

 refuses to accept it as a separate genus, and insists on its resemblance to 

 ScytotJialia, under which he places it. The receptacular branch he allowed 

 was different, but did not think it of importance. 



Klitzing records it as ScytotJialia axillaris (Species Algarmn, p. 59 2 )- 

 and Oltmanns* seems doubtfully to follow him. 



I have adhered to Greville's classification for the following reasons. 

 There is an undoubted resemblance between the two plants in their 

 structure and mode of growth which makes them very closely allied, but 

 the receptacular branches differ from each other in a marked degree. 

 Harvey, who agrees with the Grevillean classification, adds another 

 slight distinction (PJiycologia Australica, plate IV.), 'ScytotJialia when 

 steeped in fresh water throws out, like Fucus, an immense quantity of 

 slimy gelatine ; but this is not the case with Seirococcus.' On examination 

 I find the cells of ScytotJialia have very much swollen mucilaginous walls. 

 The conceptacles of Seirococcus are borne on special branches, not on 

 metamorphosed organs like those of CoccopJiora and some other Fttci. It 

 is this rather striking peculiarity which separates it from the Cystoseirae, 

 the affinity with which Turner had already questioned, and places it near 

 the Sargassece. Oltmanns, in his arrangement of the Fucacece, places it 

 under that group, and the following details of its structure confirm his 

 judgment. 



The plant has a flat stem from which side branches are given off 

 irregularly (plate x., fig. i.) These branches bear the flat sinuous fronds 

 which rise alternately at an acute angle. On the opposite edge from the 

 leaf insertion there is a narrow wing, which in turn broadens out to form a 

 frond. The fronds are simple and entire, flat and rather sinuous ; there is 

 no midrib, and they vary in width, tapering to a blunt tip, simple or bifid. 



The plant has much the same structure throughout, in stem and frond. 

 There is a central portion in the stem of long cells with very much 

 thickened walls ; a cortex of larger looser cells, and an epidermis several 



* Loc. cit., p. 70. 



