THE GENUS POLYSIPHONIA. 295 
Ag. (2) ii. p. 1022, to which it bears considerable resemblance anatomically. 
The specimen in the Herbarium Hookerianum at the Royal Botanic Gardens, 
Kew, was collected by Richardson. Harvey (28. p. 111) noticed the 
striking similarity between the branching of P. Richardsoni Hook. and 
P. elongella Harv., but remarks that there is no resemblance to any other 
character, evidently having omitted to examine the attachment organ. 
Habitat. Detailed habitat unknown. 
British Records, Colvend, Kirkcudbright (Richardson). 
Distribution in Europe. Nil. 
7. P. siMULANS Harv. Man. Brit. Mar. Alp. ed. ii. 1849, p. 89. 
P. spinulosa Harv. Man. Brit. Mar. Alg. ed. i. 1841, p. 87 (non Grev.). 
P. divergens y. Grevilleana Kütz. Sp. Alg. 1849, p. 822. 
References. Agardh (2) ii. p. 1051 ; De Toni (22) iv. p. 935. 
leones. Harvey, Phye. Brit. pl. 278. syn. 121. Æwsiceatæ. Urouan, 
Alg. mar. Finist. no. 304, 1552. Lloyd, Alg. Ouest Fr. no. 279, 1854. 
Description. —Habit. Plants tufted from the base; branches arising alter- 
nately, sparsely clothed with irregularly pinnate ramuli, the latter tapering 
sharply at the apex. Siphons. 12 pericentral round a central one of 
diameter equal to about 1-2 times the radius of the whole filament. Colour. 
Reddish-brown. Anatomy. Articulations about one and a half times as long 
as broad in the main branches, but shorter than their breadth in the ramuli 
and at the extreme base of the plant. Attachment organ. Numerous rhizoids 
are developed by the proliferation of pericentral siphons, each rhizoid bearing 
a well-formed dise at its distal end. The main branches creep along the 
substratum for a short distance, producing an aggregation of dises. Repro- 
ductive organs. letraspores intercalary in development, borne in distorted 
ramuli. Cystocarps sessile, ovate in form, borne on the smaller branches. 
P. simulans is rigid when fresh, but adheres to paper after immersion in 
fresh water. It is much darker in colour than P. subulifera. Should any 
confusion occur between some forms of this species and P. nigrescens, a trans- 
verse section at the extreme base of one of the main branches is often a 
decisive factor in determination. P. simulans is ecorticate throughout, while 
at the base of P. nigrescens there is frequently a row of corticating cells. 
The serrate appearance due to the remains of old branches so frequently to be 
observed in P. nigrescens does not occur in P. simulans. The aggregation of 
attachment discs is similar in the two species. 
Habitat. Occurring near low-water mark. Most often found on thin- 
bedded and eroded schists. Rare. 
British Records. Skaill, Studland, Swanage, Torbay, Plymouth, Mount 
Edgeumbe, Falmouth, Mount’s Bay, Arran, Cumbrae, Valentia, and 
Kerry. 
Distribution in Europe. Unknown. 
