272 



F. BORGESEN 



than 7a mm in diameter, perhaps even more, but it is difficult to tell the exact 

 size as the plants gradually get fused together. 



The basal layer is composed of irregularly ramose filaments which are 

 free at the margin, otherwise forming a monostromatic disc. The disc cells 

 measure 3 — 4 [X across and 9-12 jj. in length; often they are curved and bent. 



From this basal layer erect long assimilating filaments and sporangia 



arise. 



The assimilating filaments are simple, straight and composed of cells about 

 6 — 8 [J. wide and 15 |t long in the lower part; upwards the cells grow longer 



Fig. 17. a Acrochaetium moriiliforme Rosenv., a single plant with sporangia (two emptied) and 



a hair, c. 4no /i. b — d A. discoideum nov. spec: b, c sections through plants, in c the superficial 



cells of the host; d part of horizontal disc; all c. 400 /i. 



and become almost, colourless. The assimilating filaments attain a length of 

 about 200 — 300 u,. 



The sporangia are sometimes sessile, sometimes pedicellate. They are 

 oblong-ovate, about 11 — 13 ^ l° n g an d 6—8 \x across. 



Regarding the cell contents this was in a bad condition, the material 

 having been dried, but the chromatophore seems to be parietal with a parietal 

 pyrenoid. 



This species must be compared with Chantransia Uptonema and Ch. re- 

 ducta of ROSENVINGE, both exhibiting about the same mode of growth but 

 differing materially in other respects from A. discoideum. 



Area of distribution: Endemic. 



