ULOTRICHE^E. 183 



Wells, 188. Harv. Man. 160. Johnst. Fl. Berw. ii., 259. 

 Mack. Hib. 238. 



Conferva imiralis, 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 -Las in some of his works applied to the terrestrial species of 

 Ulothrix the generic name of Hormidium, which is only of sectional 

 value. 



Plate LXXI. fig, 1. Portions of threads of Ulothrix radicans 

 X 400. 



Ulothrix (Hormidium) parietina. (Vaitch.) Kutz, Tab. Phyc. n., 



t.Q7,f. 1. 



Bright yellowish green, flexuous and interwoven, cells half 

 as long as broad, cell membrane thin, hyaline, homogeneous. 

 SIZE. Cells -009--016 mm. 



Babh. Alg. Eur. iii., 367. Kirch. Alg. Schl. p. 78. 

 Hormidium parietinum, Kutz. Phyc. Germ. p. 193. 



On walls, trunks, &c. 



Plate LXXI, fig, 2. Portions of threads of Ulothrix parietina 

 X 400 diani. 



GEN. 68. SCHIZOGONXUM. 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 18G1 Dr. Braxton Hicks indicated his belief that Schizogonium was 

 only a condition of Ulothrix in which the threads had become connate, 

 of which PrasioZa 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 Algas. Thus the 'linear 

 stage is called Lyngbya (Ulothrix) ; the early stage of collateral seg- 

 mentation, the Schizogonium; the adult stage, the Prasiola ; while the 

 goniclial. growth has been classed under Palm ell acece." 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 



