(70) 



liiore generally very irregular, partly dichotomous, partly secund, partly 

 alternately or ojopositely pinnated, and every other variety of division 

 may be observed often on the same plant. Professor Harvey enumerates 

 three distinct varieties, the chief distinctions being the breadth of the 

 frond, with some minor differences in colour and substance. Structure 

 composed of an axial stratum, consisting of an extremely lax network 

 of very slender shortly articulated fibres, forming the greater portion of 

 the frond, and enclosed in a thin membrane composed of one or two 

 layers of very minute coloured cellules. Substance very soft and 

 gelatinous, adhering closely to paper. Colour, a brownish or reddish 

 pink, becoming darker in drying, and changing to a brownish green in 

 decay. Favellidia abundantly scattered in the form of minute dots, 

 through the principal divisions of the frond, and even extending to the 

 cilise. Tetraspores unknown. 



An ocean species, and mostly confined in the British Islands to the 

 south and west, becoming rarer as we proceed northwards, although 

 extending its range to the Orkney Islands {Pliyc. Brit). "We have seen 

 no specimens from the east coast of Britain, although we are informed 

 by the same authority that it has been found on the coast of Norfolk. 



It is one of our most variable species, scarcely less so than the pre- 

 ceding, varying gi'eatly in the breadth of its fronds, and in the greater 

 or less number of tlie proliferous processes, which are often very minute, 

 but frequently prolonged into branches having their apices entire, bifid, 

 laciniated or palmate, aud are exactly similar in structure to the rest of 

 the frond, often containing dots of fructification. 



The species is occasionally found in rock pools near low-water mark, 

 but is mostly thrown on shore from deep water, or obtained by dredging. 

 The figvires given show medium, narrow, and broad states of the fronds. 



EXPLANATION OF PLATE XCIL a, b. 



Figs. 1. A, B. — Hnlymenia Ugulata, natural sizes. 

 2. — Transverse section of frond. 

 3. — A favellidium. 

 4. — Spores from sanae. All magnified. 



