264 Richards: Ceramothamnion codii 



whole, the structure of a Ceramium with its clustered nodal and 

 bare internodal cells, and that it is furnished with polyspores 

 reminiscent of those of Ptilota. The general appearance, how- 

 ever, is very dissimilar to any of these, and it is further marked by 

 the peculiarity of the proliferating tetrasporangia. Since it is, 

 therefore, impossible to place this form satisfactorily in any of the 

 established genera, and since its peculiarities are sufficiently marked, 

 it seems justifiable to assign it to a new genus, the diagnosis of 

 which is appended. 



Ceramothamnion gen. no v. 



Plant consisting of prostrate filaments giving rise above to 

 erect filaments, and below to rhizoids. Erect and prostrate fila- 

 ments same in structure, monosiphonous throughout with small 

 cells collected at nodes : growing tip straight, never circinate : 

 chromatophores rhodophyceous, in elongated bands running almost 

 the length of the internodal cells : tetraspores, antheridia and 

 polyspores present : tetrasporangia borne at nodes : cruciate ; pro- 

 vided with enveloping sterile cells, proliferating by successive 

 formation of new tetrasporangia inside of the old. 



Ceramothamnion codii sp. nov. 



Prostrate filaments 30-50 p in diam., never branched except 

 for erect filaments which arise at nodes : erect filaments 20-35// 

 in diam., from 0.5 to 1.5 mm. long, sterile, always unbranched, 

 branches arising in connection with polyspores ; outer wall 

 usually unbroken and continuous, but at times pierced by 

 sterile hairs which arise from the nodal cells ; nodal cells in ma- 

 turity usually 12-16 at each node, never forming a complete 

 cortication to the internodal cells ; mature tetrasporangia single 

 at node, 30-45 x 20-30/*, partially covered with enveloping sterile 

 cells : proliferating as described above : polysporangia variable 

 in size, 35-60 x 50-80/* arise laterally from the erect filaments, 

 and consist at maturity of clusters of from 10 to 20 polyspores : 

 several of the clusters — from two to four — are grouped together 

 and are surrounded by protecting branches. Procarpes and cysto- 

 carps not observed. Antheridia in masses sheathing the inter- 

 nodal cells, or forming more or less rounded masses from node to 

 node. Polyspores and antheridia usually on separate plants, occa- 

 sionally on same filament. 



Habitat. — Forms minute tufts or small expanses on Codium 

 tomentosum among the cortical ramifications of which its rhizoids 



