118 SYNOPSIS OF BBITI8H SEAWEEDS. 



substance, J.Ag.. Hare. Mam, ed, 2. p. Ml. (Atlas, PI. L. 



Kg. 828.) 

 Hah. Coast of Devonshire. On rocks near low -water mark. 



Perennial. Winter and spring. 

 This species I formerly regarded as a variety of VhyU 

 lophora Brodiari, according to the views <>f in<»<t British 

 botanists. In the last edition of the ' .Manual" I have re- 

 cognized its specific existence under the name here given, 

 a name adopted from Prof. J. Agardh, who, in a recent 

 letter, points out particularly the characters which distin- 

 guish this little plant from the original P. Brodicei. These 

 characters are, — the position of the sorus of tetraspores ; 

 the brighter colour of the frond ; and the much more widely 

 expanded root. To these I would add a marked difference 

 in its geographical distribution; for while P. Brodiwi is 

 confined to our northern shores, P. palmettoides is a na- 

 tive, in this country, only of the south of England, and, on 

 the Continent, is found in the Mediterranean. 



LXIY. PEYSSONELIA. 



203. Dubyi (Dubtfs Peyssonelia) ; frond membranaceous, orbi- 

 cular or lobecl, attached by the whole of its under surface, 

 Crouan, in An. Sc. Nat. 1844. p. 368. t. 11. B. (Atlas, 

 PL L. Fig. 224.) 



Hah. North of Ireland and west of Scotland. On old shells, 

 stones, etc., in 10-15 fathoms water. Probably common on 

 the British coasts. 

 The genus Peyssonelia was founded by Decaisne, on the 

 Fucus squamarius, Gm., a species common in the Medi- 

 terranean, of larger size and more coriaceous texture 

 than the present, and attached by a portion only of its 

 lower surface. The Zonaria rubra, Grev. in Linn. Trans., 

 is probably the young of that species. I am only acquainted 

 with Kutzing's P. orbicularis by the short description 

 given in his work, by which it appears to be very closely 

 allied to our P. Dubyi, but to differ in having its lower 

 surface glabrous and closely adherent. 



LXY. GYMNOGONGKUS. 



204. Griffithsiae {Mrs, Griffiths'* Qymmog<mgrus)\ frond filiform, 

 flexuous, cartilaginous, stipitate, many times dichotomous, 



the apices fastigiate, forked ; warts of fructification oblong, 



