excessively branched, distichous ; branches alternate or scattered, the smaller 

 ones more or less pinnately compound, long and short intermixed irregu- 

 larly, the smaller ones more equably and closely pinnate or bipinnate. 

 Every portion of the frond, except the denuded parts of old stems and the 

 bases of old branches, is closely pectinated with small, subulate, distichous, 

 flat or compressed, spreading ramuli or cilia, 1^-3 lines long, slightly de- 

 current at base. The rachides of the branches are thickened in the middle 

 into a rib, which usually occupies the greater part of the width, leaving a 

 very narrow or obsolete border. The conceptacles (?), as well as the recep- 

 tacles, are axillary and pedicellate. The conceptacles, on all the specimens I 

 have seen, are abortive, irregularly formed, and contain no perfect spores ; 

 they are subglobose, depressed on the summit, and often partially bivalve or 

 irregularly gaping. Receptacles of tetraspores are egg-shaped, containing 

 numerous cavities excavated under the surface-coating, and bearing on their 

 walls attached, elongated, clavate or filiform zonate tetraspores, not unlike 

 the strings of spores of a Coralline. Mixed with these are unicellular para- 

 nemata. Colour, when growing, a very dark red, after long immersion or 

 exposure changing to a deep-crimson, and then scarlet and orange. Substance 

 very firm, cartilaginco-corneous, rigid when dry. In drying, the frond does 

 not adhere to paper. 



A well-known and abundant Alga along all the extratropical 

 coasts of Australia, agreeing in ramification and general habit 

 with several others, but readily known from all by its very cu- 

 rious fructification. I have abstained from figuring what are 

 called conceptacles {cystocarps) in this genus, because I am by 

 no means assured that they really are cystocarps, and because I 

 think they may probably be only abortive receptacles, or perhaps 

 antheridia-cups. In the many specimens I have examined I have 

 never found well-developed spores, and very frequently only an 

 amorphous mass of tissue. It may perhaps be questioned 

 whether the receptacles themselves may not be true cystocarps, 

 and the so-called tetraspores, strings of spores similar to the 

 quaternate spores of Corallina. Were this view admitted, the 

 affinities of Pliacelocarpus would be with the Gelicliacea. At 

 present it is quite uncertain to what family this genus should be 

 referred. 



Fig. 1. Phacelocarpus Labillardieui ; a branch, — the natural size. 2. 

 Small fragment of a branch, in fruit. 3. Cross section of the stem. 4. Small 

 fragment of the periphery of the same. 5. Longitudinal section through a 

 receptacle, showing many tetraspore-cavities. 6. Tetraspores and parane- 

 mata from the same : — variously magnified. 



