189 



often been confounded with other species. It was only by becoming acquainted 

 with the recently pul)lished description of Peijssoimelia {Cruoriella) Nordstedtii Weber- 

 van Bosse ' and by the final revision of my material that I arrived at the conclu- 

 sion that it was not identical with the former, but more resembled the last named 

 species. As it proved to be dilTerent also from this and did not appear to agree 

 with any other well known species, I describe it here as a new species. 



Cruoriella codana has only been met with once on a calcareous stone much 

 bored by worms. It forms thin crusts of a bright purple colour, brighter than in 

 Cr. Dubyi, and is adherent to the substratum in its whole extent, being fixed to it 

 by unicellular rhizoids. The greatest crust is more than 5 cm in diameter, but it 

 has probably arisen by coalescence of several distinct crusts; the other were at 

 most 1 cm broad. When seen from Ihe underside, the young basal layer appears 

 composed of distinct lobes, which coalesce laterally. The lobes have a flabellate 

 structure. Even when having a continuous outline, the margin is composed of very 

 distinct lobes (fig, 112 A), and the same structure is found in the older parts of the 

 hypothallium, where there are no principal rows of larger cells, as found in P. 

 Boergesenii and P. Nordstedtii by Mrs. Weber-van Bosse (1. c. p. 138 and 140). The 

 cells of the basal layer are 14 — 33// long, 9 — 14/; broad and 9— 11/^ high. Uni- 

 cellular rhizoids, bounded by a cell wall, are given off from its under face. The 

 marginal cells of the frond divide by vertical cell-walls, and the segments divide 

 immediately by a horizontal wall, the hypothallic cell becoming thus lower than 

 the marginal cell (fig. 114). The monostromatic basal layer or hypothallium is only 

 little distinct from the "perithallium" consisting of the vertical filaments given off 

 •from it. These filaments are vertical in their whole extent or slightly ascending; 

 they are only rarely branched. The cells are of almost equal breadth in the same 

 filament, 9 — 12 fi, or the undermost may be a little broader. Their height is as a 

 rule a little less than the breadth, near the surface sometimes much less, more 

 rarely the same or a little greater. The number of cells in the erect filaments 

 usually varies from 3 to 10. 



Old crusts are composed of two or more fronds growing one over the other. 

 At first observation these superposed fronds might be supposed to come into exi- 

 stence in the same way as recently described by Mrs. Weber-van Bosse in Peijs- 

 sonnelia (Cruoriella) Nordstedtii (1. c. p. 141, fig. 146), by the formation of a horizontal 

 split in the frond and following constitution of the part situated over the split as 

 a new crust wdth a new-formed hypothallium. I have seen several cases which were 

 - favorable to this interpretation, in particular some apparently young cases and such 

 where the under face of the upper crust was very irregular, and I might suppose 

 that the new upper frond may really arise in this manner. But in other cases it 

 is without doubt that the upper frond arises from horizontal outgrowths from certain 

 parts of the crust which have preserved their growing power, while the covered 



' Rhizophyllidacese in F. Borgesen, RhodophyccEe of tlie Danish West Indies. Dansli Botan. Arkiv, 

 Bd. 3. Nr. 1, 1916, p. 140. 



