ULOTRICHEA. 183 
-Wells, 188. Harv. Man. 160. Johnst. Fl. Berw. ii., 259. 
Mack. Hib. 238. 
Conferva muralis, Dillw. Conf. t. 7. Eng. Bot. i., t. 1554. 
Humida muralis, Gray Arr. i., 282. 
Oscillatoria muralis, Grev. Fl. Ed. 304. Fl. Dev. ii., 57. 
Hook. Fl. Scot. ii, 79. 
On the naked ground, rocks, walls, &c. 
Kutzing has in some of his works applied to the terrestrial species of 
Ulothri# the generic name of Hormidium, which is only of sectional 
value. 5 
Plate LXXTI. fig. 1. Portions of threads of Ulothrix radicans 
x 400. 
Vlothrix (Hormidium) parietina. (Vauch.) Kutz. Tab. Phyc. 11., 
t.9 ‘ 
aJ° 
Bright yellowish green, flexuous and interwoven, cells half 
as long as broad, cell membrane thin, hyaline, homogeneous, 
Size. Cells ‘009-016 mm. 
Rabh. Alg. Eur. iii., 367. Kirch. Alg. Schl. p. 78. 
Fformidium parietinum, Kutz. Phye. Germ. p. 1938. 
On walls, trunks, &. 
Plate LXXI, fig. 2. Portions of threads of Ulothria parietina 
x 400 diam. 
Gey. 68, SCHIZOGONIUM. Kutz. (1843.) 
Threads as in Ulothrix, or in many places laterally connate 
(duplicate or triplicate), or by cellular division in two directions 
forming narrow flat bands, which are more or less crispate. 
In 1861 Dr. Braxton Hicks indicated his belief that Schizogonium was 
only a condition of Ulothriz in which the threads had become connate, 
of which Prasiola was only a frondose form. He says, “the whole of 
these changes are so palpable, can be observed so constantly, and are, 
at the same time, so simple in their relations to one another, that one 
can scarcely imagine how they can have been separated, not only into 
distinct species, but into different families of Algz. Thus the linear 
stage is called Lyngbya (Ulothrix); the early stage of collateral seg- 
mentation, the Schizogonium; the adult stage, the Prasiola ; while the 
gonidial growth has been classed under Palmellacee.” And again, 
“ the only real difference between the first two is, that whereas Lyngbya 
(Ulothrix) is a tube containing distinct cells within, which, when old 
undergo collateral subdivision, to form a band of two, four, or eight 
rows of cells, Schizogonium is a band of two or eight rows of cells, 
which, when young was but a single row,contained in a tube, which 
is only two different ways of stating the same facts. The comparison 
of the last two is of the same kind. For as Prasiola, when old, is com- 
posed of many rows of cells, but which arose from a single row, there 
must have been a time in its life when it had two, four, or eight 
rows, and thus have been a Schizogonium, for there is no other 
