298 DR. LILY BATTEN ON 
The fact that the ramuli are attenuate at the base and apex is one of the 
distinguishing features of the species. P. elongata has been described as 
being either biennial or perennial, but close observation of individual plants 
has show n that it is perennial. According to Falkenberg (24. p. 126), the 
older plants may show a secondary development in which the cavities of the 
siphons become filled with small cells, comparable to those forming the corti- 
cation, although the wall of the original siphon is still visible. The attachment 
organ is one of the most elaborate found in the genus, Its development can 
doubtless be correlated with the corticate anatomy of the plant and its 
solitary habit. There are no procumbent branches present whieh can aid in 
the attachment, but the large number of siphons and corticating cells make it 
possible to develop a strong organ of attachment from the main axis alone. 
At the extreme base the corticating cells spread out in a more or less hori- 
zontal direction, so giving an increased surface for the development of rhizoids, 
In the greater part of the large expanded dise the walls of the rhizoids 
cohere mechanically, forming a pseudo-tissue (see p. 279 ef seg.). | 
Habitat. Attached to stones and shells in pools and muddy bays between 
the tide-levels and in from 5-10 fathoms of water. Common. 
British Records, Scotland, Northumberland, Durham, Yorkshire, Norfolk, 
Essex, Kent, Sussex, Hants, Dorset, Devon, Cornwall, Hilbre Island, Wales, 
Treland, and Jersey. 
Distribution in Europe. Atlantic and Mediterranean shores. 
. P. ELONGELLA Harv. in Smith’s s Engl. Flora, v. 1833, p. 334. 
P. lophuroides Kütz. Tab, Phyc. xiii. 1863, p. 28,tab. 91 (ab). 
References. Agardh (2) ii, iii. p. 1002; De Toni (22) iv. p. 910; 
Hauck (31) p. 228. 
Icones. Kützing, Tab. Phye. xiii. 1863, tab. 91 (a-b). Harvey, Phye. 
Brit. pl. 146. syn. 113. — /esiecata. Wyatt, Alg. Damnen, no. 84. 
DESCRIPTION. — Habit. Plants as much as 13 cms. in height, usually solitary, 
Branching pseudo-dichotomous with wide angle of divergence e, in the main 
branches, alternate in the smaller branches, which are densely clothed with 
ramuli during the spring and summer. Upper parts gelatinous in substance, 
basal parts cartilaginous. — Siphons. 4 primary pericentral, alternating 
with which 4 secondary occur bounded by a band of corticating cells, 
Colour. Bright red in the ramuli, darker in the lower parts of the plant, 
Anatomy. Articulations rather shorter than their breadth at the base, about 
equal to their breadth in the main branches, and in the ramuli very short nea 
the apices, increasing in length proximally. Attachment organ. Ver y similar 
in form to that of P. elongata, the siphons and cortie ating cells elongating 
longitudinally into thick-walled rhizoids which cohere mechanically with 
cach otber, forming a pseudo-tissue. Reproductive organs. Tetraspores 
