62 Ellen Marion Delf 



or epiphytic on the larger Algae. Various species of Pol^si- 

 phonia may be found as delicate soft red tufts in the deeper creeks 

 and sheltered pools of St. James and Kalk Bay. Various species 

 of Ceramium may also be recognised by the beaded appearance 

 of their regularly branched threads. These and many other 

 seaweeds may be seen by the collector on application at the Bolus 

 Herbarium, Cape Town. 



In addition to this zonation which extends over the whole tidal 

 area of the shore, there is a vertical zonation which is sometimes 

 very clearly to be seen amongst the algae which line the steep rock 

 faces of the deeper pools. At the top, well out of the water may 

 be seen the half dry fronds of Porph})ra laciniata; lower come 

 the smaller and more delicate monosporic fronds of the same plant. 

 Within the pools there are often green feathery tufts of Clado- 

 phora or of Chaetomorpha, sometimes called " mermaids' hair,'* 

 while beneath there are plants of Cigartina or of Poly^siphonia, 

 and the smaller kinds of a stiff looking pink jointed seaweed known 

 as Coralltna. At a depth of about two feet, one frequently finds 

 small fanlike fronds of a red Alga, C};mnogongrus vermicularis. 

 The fronds are always extended so as to be placed at right angles 

 to the direction of the brightest light. The bifurcated tips are so 

 placed that they interlace, offering the maximum surface to the dim 

 light which reaches them. This is the most striking case which I 

 have seen of a definite orientation of fronds of seaweeds to light, 

 comparable to the well known cases of leaf mosaic among the 

 higher plants. 



Another point of interest in connection with marine Algae is 

 their common habit of becoming epiphytic or parasitic upon each 

 other. The smaller red Algae sometimes have their own specific 

 host plant. For instance, on these shores, Ceramium cancellatum 

 is commonly found on C odium iomeniosum; Actinococcus 

 aggregatus on Cy^mnogongrus repandus; and Callithamnion pur- 

 puriferum, on Cigartina stiriata. On the other hand, certain Algae 

 serve as hosts to a variety of other Algae. The various species of 

 Cladophora are often coated with epiphytes, their rough walls 

 serving as an excellent support. Ecklonia buccinalis in spite of 



