"1 



Fronds branched dichotomously at top of broadened joint, rarely trichotomously, with 

 adventitious branches springing from the joints not trom the nodes; joints flattened, two-edged, 

 at base of plant sometimes cylindrical and sometimes much flattened and broadened; upper joints 

 almost always flattened, rarely a cylindrical joint between flat ones. The top joints as a rule 

 a little fan-shaped, distinctly zonate, less so if top joint is, - - as seldom happens - - almost 

 cylindrical or bears conceptacula. 



Central strand of 2, 3, 1 or 5 rows of long cells, foliowed by a row of very short cells. 

 1 leieju of long cells from 36 — 140 u, height of short cells 12, 16, 20 v.. Rows of cells spreading 

 fan-like from the centre towards the periphery. Cortical layer relatively thin except in old joints. 



When the broadened top joint is going to divide, there appear two little short cylinders 

 of non-calcified tissue consisting of a part only of the central strand. These short cylinders 

 are to be the two nodes; the cells constituting the nodes increase slightly in number, thicken 

 their membranes and grow till they have the size of the adult node. The remaining portion 

 of the central strand and the cortical layer adhering to it, remain calcified and separate 

 around the nodes. 



Three little teeth of calcified tissue surround the base of the two nodes, one at each side 

 and one in the middle. The node itself is however later on surrounded by a young layer of 

 non-calcified cortical cells, and by their repeated divisions the node increases in thickness with 

 the thickness of the frond. In some specimens the two nodes touch one another at the base 

 and 110 little tooth of calcified tissue is observed between the nodes which are then practically 

 only one node at their base, which divides in apical direction into two portions. 



Conceptacula appear as a rule only on one side of the joint, but sometimes on both 

 sides. They are slightly prominent and have a diameter from 250 — 410 u.. I have seen con- 

 ceptacula with tetraspores and with antheridia. 



Amphiroa anceps was described by Lamarck under the name of Corallina anceps from 



New Holland; a few years later Lamouroux described the same alga from the Cape under the 



name oi A. dilatata. Akeschoug pointed out the great affinity between A. dilatata, anceps and 



rbankii but maintained the three species. My collections give me entire justification for sinking 



A. dilatata in A. anceps, which name as the older one must be maintained. The joints of A. anceps 



differ so much, even on the same plant or on different plants from the same locality, that the 



limits must be made very large. Specimens with long, flat, zonate joints, with nodes having 



e little teeth and with conceptacula in two rows on one side of the joint wil! be found inter- 



mingled with joints with obtuse border, not so compressed and without the characteristic teeth. 



1 he nodes of all these plants have this in common that they consist of a part of the 



central strand. The two nodes in one articulation may remain isolated each by itself or adhere 



h( r al their base, and this may be observed even in the same plant. The cortical layer 



ring to the nodes increases in thickness with the thickness of the frond and can in old 



fronds attain a considerable dimension. 



1 he central strand is built up of two, three, four or five rows of long cells foliowed by 



row oi shorter cells and then a row of very short cells 8 — 12 <j. high. These two latter 



tot always to be found. sometimes there is only one row of 20 — 40 n. high. The 



