I 
74 Bristol . — On the Alga-Flora of some Desiccated 
envelope in which the young cells remained embedded for some time. In 
some cases a second division took place before the separation of the young 
cells, so as to produce groups of four cells enclosed in a common muci- 
laginous envelope. 
This species has not previously been recorded for the British Islands. 
4. Trochiscia aspera, (Reinsch) Hansg. 
This very widely distributed species was obtained from thirty-four 
different soil-samples. In many cases the form observed was exactly 
typical of the species ; but this species showed perhaps more than any other 
a tendency to change as the result of cultural conditions. The cells were 
spherical or subspherical, 14 to 20 n in diameter or more rarely up to 33 /x, 
with several parietal chloroplasts, some of which contained a single pyrenoid, 
in each cell. In the normal form the cell-wall was ornamented with 
prominent denticulations connected together by low ridges, but in the 
cultures this character tended to be suppressed, the denticulations becoming 
less prominent and the ridges almost absent ; there was, however, no reason 
for thinking that these cells were other than abnormalities, since every 
gradation could be found between the two extremes. A palmelloid state 
exactly similar to that figured by West 1 was frequently observed. 
Multiplication was by the production of non-motile gonidia. 
5. Trochiscia hirta , (Reinsch) Hansg. 
In genera] features and in its life-history this species agreed completely 
with the last, but it differed in the character of its cell- wall. Instead of 
having comparatively few prominent denticulations, the wall was ornamented 
with very numerous minute spines so closely crowded together as to give it 
an almost granular appearance. It occurred in two soils. 
6. Ankistrodesmus falcatus , (Cord a) Ralfs, forma terrestris (Text-fig. 2 ). 
The cells of this form, found in only one soil, were lunate, but some- 
what narrow, with acute apices. They were 2 to 2-5 /x broad by about 18 /x 
long, and contained a single chloroplast, usually devoid of a pyrenoid but 
very occasionally containing one. Multiplication was observed by the 
production of four or eight autospores which, on the gelatin ization of the 
mother-cell wall, usually remained loosely attached together by one end 
(Text-fig. 2 y d). The further production of autospores in the same way 
gradually gave rise to the formation of loose and somewhat irregular 
colonies, as shown in Text-fig. 2 , e. j 
7. Dactylococcus bicaudatus , A. Br. 
This species was found in one soil The cells were lunate with greatly 
prolonged apices, and contained a single rather small chloroplast devoid of 
a pyrenoid. The length of the cells was 20 to 25 /x, and the breadth 
3*5 to 5 fji. Multiplication was observed to occur by the production of four 
autospores. 
1 West, G. S. : British Freshwater Algae. Cam. Biol. Series, 1904, Fig. 82, F. 
