Scr. MELANOSPEKMEiE. Fam. Fucacece. 



Plate IV. 



SEIROCOCCUS AXILLARIS, Grev. 



Gen. Chae. Root branching. Frond distichous, linear, midribbed, alter- 

 nately decompound; the branches vertically flattened, pinnatifid. 

 Vesicles none. Receptacles distinct, fringing the margin of the laci- 

 niae, moniliform, slender, of densely cellular substance, poriferous, 

 containing under each pore a monoecious spore-cavity. Spores obovoid, 

 subsessile. Antheridia oval, on branching filaments. Faranemata 

 simple. — Seirococcus [Grev.) from aecpa, a chain, and kokkos, a 

 berry ; because the receptacles are chain-like. 



Radix ramosa. Frons disticha, linearis, costata, alterne decomposita, ramis ver- 

 ticalibus pinnatifidis. Vesiculce nulla. Receptacula propria, secus margi- 

 nem evoluta, moniUformia, gracilia, dense cellulosa, ostiolis pertusa. Sca- 

 p/iidia monoica. Sporce obovoidea;, subsessiles. Antheridia racemosa. Para- 

 nemata simpliciuscula. 



Seirococcus axillaris, Grev. 



Seirococcus axillaris, Grev. Alg. Syn.p. xxxiv. Endl. 3rd Suppl. p. 33. J. 

 Ag. Sp. Alg. v. 1. p. 260. 



Scytothalia axillaris, Mont. Voy. Pol. Sud, v. 1. p. 86. Kiitz. Sp. Alg. p. 593. 



Cystoseira axillaris, Ag. Sp. Alg. p. 80; Syst. p. 291. 



Fucus axillaris, R. Br. in Turn. Hist. Fuc. t. 146. 



Hab. In the Laminarian zone. South coasts of New Holland, east of Cape 

 Northumberland, and on the shores of Tasmania. 



Geogr. Distr. Not known beyond the above limits. 



Descr. Root a disc, throwing out numerous radiating branched and clasping 

 fibres. Frond 3-6 feet long or more, distichous, alternately decompound, 

 with a nexuous rachis, as if the proper ramification were dichotomous, but 

 one fork of the dichotomy regularly alternately suppressed throughout. 

 The stem is compressed, about two lines broad, and about 2-3 inches in 

 length to the first branch ; thence upwards it becomes more compressed, 

 and at length flattened, linear, and traversed by a flat, immersed rib, which is 

 continued to the apex, and is more or less evident in all the branches, but 

 not in the ultimate laciniee. The branches issue from the sharp edge of the 

 stem, are subfiliform, but compressed at base, like the stem, flattened up- 

 wards, linear, ribbed, flexuous and pinnatifid ; laciniae 'linear-strap-shaped, 

 somewhat falcate, obtuse or subacute, 4-6 inches long, and rather more 

 than \ inch broad. Receptacles 2 lines long, pedicellate and apiculate, fili- 

 form, becoming verrucose or moniliform as they approach maturity, deve- 

 loped along the margin both of the rachis and of the lacinias, and sometimes 

 densely fringing these parts for some inches in extent, at other times not 



