MR. G 5. WEST ON SOME CRITICAL GREEN ALG. 285 
Kirchneriella subsolitaria differs from the three previously known species of 
the genus in the subsolitary habit and the entire absence of mucus. In the 
form of its cells it greatly resembles A. obesa, but apart from its different 
habit it is much smaller. 
The genus Airchneriella was founded by Schmidle! in 1893 to include а 
small protococcaceous Alga which had been regarded by Kirehner as an 
Ankistrodesmus (= Fhaphidiwm). This plant, Kirehneriella lunaris, Schmidle, 
and another species, А. obesa, W. & G. S. West?, have been shown to be 
fairly abundant in the European freshwater plankton, the latter being 
sparingly distributed in the summer plankton of the lakes of Western 
Scotland”. А third species, A. contorta, (Schmidle) Bohlin, is known from 
Germany, and var. gracillima of it from South America *. 
The most important generie character, which is well marked in all the 
three species and. several named varieties of. them, is the somewhat irregular 
disposition of a number of arcuate cells within a copious structureless 
mucilage. As will be seen from the description of the newly discovered 
species, this generie character will have to be modified for the inelusion 
within the genus of K. subsolitaria. 
This undescribed species was found in October 1906, among numerous 
other Algie of the Protococcacew, in a collection made from а small pond in 
Studley Park, Warwickshire. The cells agree almost exactly with those of 
№. obesa, but are much smaller. They are stout and much bent, but show a 
greater irregularity of form than is seen in XK. obesa. Very often one limb 
of the cell is much thicker than the other (figs. 21-23), or both limbs may be 
much attenuated (fig. 20). Теге is a chloroplast filling up the greater part 
of the cell, but in some cases not extending quite to the poles. This chloro- 
plast has a homogeneous structure, and is without pyrenoids or any trace of 
eranulation, Most of the cells were solitary, but small colonies of 2 or 
4 cells were not uncommon (figs. 26-30). The cells in each colony were 
enclosed in a thin, firm membrane, globular or ellipsoidal in form, which 
fitted closely round them. This membrane is the dilated wall of the mother- 
cell, which, however, does not undergo gelatinization. No colony of more 
than four cells was observed, and no mucilaginous envelope is present aronnd 
either the solitary cells or the small colonies, It is this absence of enveloping 
jelly that necessitates a slight modification in the generic characters of 
Nirchneriella in order to include А’. subsolitaria. 
! W, Schmidle in Ber. паби, Ges. Freib.-i.-Br. Bd. vii. (1893) p. 15, t. 3, ft, 2, 3. 
= W. West & G. S. West in Journ. Коу. Microscop. Soc. (1594) p. 16; Schmidle in 
Flora, lxxxviii. (1894) р. 44. 
3 W. West & G. S. West in Journ. Linn. Soc., Bot. xxxv. (1903) p. 531 ; in Trans. Roy. 
Зое. Edin. xli. part iii. no. 21 (1905) p. 489. 
‚ К. Bohlin, Algen der Erst. Regnell’schen Expedit., Bih. till К, Sv, Vet,.- Akad, Handl. 
34. 23. Afd, iii. no. 7, p. 20, t. 1. ff. 25-27. 
LINN. JOURN.—BOTANY, VOL. XXXVII. X 
