OF SOUTH AUSTRALIA. 
309 
and laterally branched ; the branches passing into the bases of the network, 
through which they are continued to the summit as midribs. The frond 
consists of a double system of growth; an axis or skeleton which forms 
a framework, and a superficial network. The axis is externally inarticulate, 
but formed of numerous longitudinal cells surrounding a central cell. It 
emits distichously at intervals of about 4 mm. lateral polysiphonous ramuli 
which spread subhorizontally and constitute the nerves of the penninerved 
frond. Over this closely pinnated framework is spread the net, which is 
composed of anastomising eonfervoid ramelli that issue from the sides of 
the midrib and nerves; the extremities are free and stand out from the 
surface like hairs. The general form of the frond resembles that of an 
oak leaf, between lyrate and pinnatifid ; the margin is fringed with teeth- 
like, multifid fibrils, which disappear in old specimens. In the winter 
season the stems become partially or wholly denuded, and are then found 
bearing fruit of both kinds. The cystocarps always spring from the midribs 
and generally near the summits, one on each lobe ; they are shaped some- 
thing like an amphora with a long projecting neck. The stichidia are 
formed only on ttjg lateral nerves, likewise towards the apices of the lobes ; 
and what may be called the tetrasporic inflorescence, constitutes an ovate, 
distichously pinnated, compound spike ; each individual stichidium being 
very minute, roundish, and producing three or four tetrasporangia. The 
substance though tender is not gelatinous, and does not soon decay in fresh 
water. Colour rosy or brownish-red ; adheres closely to paper. 
South Australia (Encounter Bay, Investigator Strait, Eastern Bays), 
Kangaroo Island, West Australia. 
Thuretia teres Harvey. 
Network compressed terete, bi-tripinnatifid ; laciniae linear, cylindrical, 
obtuse, without lateral nerves; articulations twice as long as broad; 
stichidia ovoid, binate or ternate, springing from the midrib, their pro- 
longed apices passing into the threads of the network. 
Attachment or holdfast spongy. Fronds densely tufted, 4 cm. to 
10 cm. high, and as much in the expansion of the branches, bi-, tri-, 
or pluri-pinnatifid, the laciniae, varying from 2 mm. to 6 mm. in diameter, 
terete or compressed. Each frond consists of a percurrent, con- 
tinuous axis or main filament, which emits lateral, distichous, opposite 
or alternate branches, this axis and its branches wdiorled through- 
out with closely placed eonfervoid ramelli, which spread horizontally; 
these ramelli are formed on a dichotomous type, but their branches 
anastomose continually into the meshes of a loose, spongy network, 
which thus imperfectly encloses the axis, and constitutes the visible 
frond. The apices of the ramelli are free and project from the surface of 
the spongy branches of the network. The stichidia are developed in the 
bases of the anastomosing ramelli, constituting the net, a little above the 
point where these issue from the axis; they are ovoid, or shortly fusiform, 
two or three growing together, and each contains a few large, irregularly 
placed tetraspores. Antheridia are formed on free processes of the ramelli 
