II5 
material collected at Port Erin a single parietal chromato- 
phore was discernible almost covering the cell wall; a 
single somewhat indistinct pyrenoid was also to be seen in 
each cell. 
14. Acrochaetium (Chantransia) emergens, Rosenv. 
Minute endophytic filaments creeping within the 
substance of the cell wall of Polystphonia spinulosa var. 
major (itself an epiphyte on Desmarestia aculeata) have been 
identified by Professor Rosenvinge as Chantransia (Acro- 
chaetium) emergens, a species which he described for the 
first time in his ‘““Marine Algae of Denmark,”’ Part I, p. 128. 
This plant corresponds very closely with a specimen 
described by Batters from material collected by Brebner 
at Plymouth (“ Journal of Botany,” 1896, p. 386) under the 
name of Acrochaetium endophyticum. The Plymouth 
material was endophytic in the cortical layers of 
Heterosiphoma coccinea (Dasya coccinea). The difference 
between the two species appears to be somewhat slight. 
Apart from the fact that they occur on different host 
genera, the main point of distinction lies in the length of 
the erect filaments that emerge through the wall of the 
host and bear the monosporangia ; in Chantransia emergens 
the monospores arise on single-celled filaments and are 
five to six mw in length by three to four yw in breadth, 
but in Acrochaetium endophyticum the nearly globular 
monospores are borne on filaments of several cells in length. 
In other respects the plants appear to be identical. They 
may represent two forms of the same species but if they 
do not, Acrochaetium emergens, Rosenv. must be recorded 
as new to the British algal flora. 
15. Sterrocolax decipiens, Schm. 
There has been in the past much uncertainty as to the 
exact nature of rounded emergences on the thallus of 
Ahnfeliia plicata. They have alternatively been described 
