Descb. Root a broad, fleshy disc. Fronds mostly solitary, 12-18 inches in 

 length. The lower part of the frond, in old specimens, becomes gradually 

 thickened into a stem, which is at first compressed, and bordered with a 

 narrow wing, and afterwards is terete, without margin or marginal teeth. 

 Upwards this stem gradually passes into the flat, narrow-linear, costate, 

 simple or forked principal-rachis of a repeatedly decompound frond. The 

 branches and all their divisions are alternate, and distichous, and more or 

 less pinnated ; but the ramification is very unequal, long and short ramuli 

 often alternating without order. In some specimens the larger branches 

 are naked below, but closely and somewhat flabellately pinnate above. 

 The branches are uniformly about a line in diameter. All the younger 

 ones are closely serrated with alternate, subulate, erecto-patent teeth, 

 somewhat longer than the breadth of the branch. The conceptacles are 

 borne just below the extremities of the ramuli, and are seated on the flat 

 surface, their base coinciding with the apex of the midrib ; they are 

 obliquely ovate, and have a terminal pore pointing upwards. The warts 

 in which the tetraspores are imbedded are of irregular form, and developed 

 in dilated apices of the ramuli, being prominent towards both surfaces; 

 the tetraspores are fusiform, and stand vertically in the wart. The colour 

 is a dark blood-red, soon fading in fresh-water. The substance is firmly 

 cartilaginous, and the plant very imperfectly adheres to paper in drying. 



Of the genus Delisea, six species are now known, five of 

 which are Australian, and one South African. These are placed 

 by J. Agardh under three subgenera, distinguished by some dif- 

 ferences in the structure of the frond, and the position and 

 structure of the conceptacles. All agree in general aspect. The 

 present belongs to the subgenus Calocladia. 



The " type of form '' to which these plants belong is found 

 in several other Australian Algae of very different affinities. 

 The genus Phacelocarpus, founded on " 'Fucus Labillardieri" of 

 Turner, is one of the best-known examples of this type; and 

 more than one species of Ftilota {Ft. silimdosa, Ft. striata, and 

 Ft. rliodocallis) are also referable to it. Some of these plants 

 are externally so similar to each other, that, although by their 

 fructification they are placed in widely separated genera, yet it 

 requires a sharp eye to distinguish them, without reference to 

 the fruit. Students must bear this in mind when using the 

 Plates here given. 



Fig. 1. Delisea pulchra, — the natural size. 2. Pinnules with conceptacles at 

 their apices. 3. Vertical section of a conceptacle. 4. Spores from the 

 same. 5. Apex of a ramulus, with a wart (nematkecium). 6. Cross section 

 through the same, showing the structure of the frond, and the external 

 growth of the wart. 7. Tetraspores and paranemata from the same : — 

 the latter figures variously magnified. 



