45 



We have not examined A. asari/olia, but we recognise at once the similarity of 

 structure in it (fig, 117) and in A. ainadelpha, namely the tortuous, branched, irregularly swollen 

 peripheral filaments felted into a pseudo-cortex of the frond. The two species are of course totally 

 different in geographical distribution. In habit moreover they are quite distinct, A. asarifolia 

 (fig. 116) being a simple plant with unbranched stipes, whereas A. amadelplia (figs. 114 and 112) 

 has two or more fronds on a branched stipes, many stipites arising sometimes from the same 

 compact rhizome. A. asarifolia bears the same relation to A. amadelpha of the Indian Ocean 

 that A. sordida of the West Indies bears to A. lacerata of the Pacific and Indian Oceans. 



3. Rhipiliopsis gen. nov. 

 (Figs. 1 18 — 1 22). 



Thallus green, not encrusted with lime, shortly stipitate, excentrically subinfundibuliformly 

 peltate to flabellato-rotundate, thin, rarely zonate, ecorticate, margin entire or lobed; filaments of 

 frond cylindrical, thin-walled, very laxly interwoven, repeatedly dichotomously branched; branches 

 much constricted at their base. Filaments often laterally attached here and there by a pseudo- 

 conjugation of two short lateral prominences one from each of the two respective filaments, 

 the two prominences often of unequal length ; but the filaments rernain persistently separated 

 by a septum. In the older filaments these junctions break asunder, leaving a number of short 

 conspicuous protuberances on the filaments. 



1. Rliipiliopsis peltata nov. comb. 



Syn. Udotea peltata J. Ag. Till Alg. Syst. V. 18S7 p. 74. 



Hab. INDIC. Fort Phillip Heads, Australia. J. Bracebridge Wilson, in Herb. Mus. Brit! 



Plants green, up to 4.5 cm. long, consisting of stalk and frond; stipes short, 2 — 4 mm. 

 long, up to 1 mm. thick ; frond varying from excentrically peltate and somewhat infundibuliform ■ 

 to flabellately expanded, rotundate, measuring 2 — 4 cm. in width, varying from entire to lobate 

 or sometimes lacerate, thin, rarely zonate, ecorticate. 



Filaments of frond slender, 12 — i8 ( u in diam., thin-walled, cylindrical, with occasional 

 short prominences about 8 u. long, very laxly interwoven, repeatedly dichotomously branched, 

 angle of dichotomy wide, branches narrowly and conspicuously constricted where they leave 

 the dichotomy. Filaments immediately below a dichotomy often 23 u in diam., young apical 

 branchlets often subspherical, 22 u. in diam. [Figs. 118 — 112]. 



This species was described by J. G. Agardh (1. c.) from specimens collected by 

 Mr. J. Bracebridge Wilson at Port Phillip Heads in 1892 — 3. Authentic specimens of these 

 are now preserved in the British Museum (fig. 1 1 8), and other specimens, both dried and in 

 spirit, of the plant are also in that Institution under another earlier and unpublished name. 

 all collected at Port Phillip Heads. 



Agardh 's description of the external habit of the plant is very gpod, but that of the 

 internal structure is misleading and indeed erroneous ; for the frond has not a cortex such as 



