300 University of Californm Puhlic^tiojis in Botany [Vol.8 



Pseudopringsheimia apicidata is closely related to P. conflucns 

 (Rosenv.) "Wille. The most conspicuous difference is to be foiuid 

 in the shape and size of the zoosporangia, if the terminal reproductive 

 cells are to be designated as such. Those of P. confluens are long 

 and comparatively narrow, and produce 30^0 zoospores, while in 

 P. apiculata they are shorter, somewhat swollen, mostly with a pro- 

 nounced terminal projection, and produce about 8 zoospores. These 

 reproductive bodies are very small, and 'it is exceedingly difficult to 

 determine the number of cilia. On one occasion four cilia were 

 observed but the reproductive bodies seemed a little larger and some- 

 what more irregular in form than the average. These may have been 

 the zj^gotes formed by the fusion of 2-ciliated gametes, but had not 

 yet come to rest. 



33. Gomontia Born, and Flah. 



Thallus consisting of creeping, freely branched, septate filaments, 

 from the under side of which many erect, more or less branched fila- 

 ments arise ; cells irregular in shape and size, uninucleate, occasionally 

 multinucleate, with parietal, band-foi^m or shield-shaped chromato- 

 phore covering the whole or part of the cell, or a network extending 

 through the cell, with one or two pyrenoids ; reproduction by zoo- 

 sporangia, producing a few egg-shaped zoospores with 4 cilia, by 

 large, irregularly shaped, thick walled, gametangia (?) with rhizoidal 

 outgrowths, producing 2-ciliated gametes (?) whose conjugation is 

 unknown, and by similar large cells producing aplanospores. 



Bornet and Flahault, Note sur deux algues, 1888, p. 163 (Repr., 

 p. 5) ; Sur quelq. pi. viv. dans le test calc, 1889, pp. clii-clx, pi. 6-8, 

 10, fig. 3. 



The genus Gomontia is composed of species having the peculiar 

 and presumably distinctive habit of boring into calcareous material. 

 They are usuall}^ to be found boring into shells of mollusks, chiefly 

 lamellibranchs, of both fresh and salt waters. One species {O. codio- 

 lifera (Chodat) Wille), however, bores (?) into limestone rocks. We 

 have considered, as chief characteristic of this genus, the formation 

 of large "sporangia" (gametangia ( ?) and aplanosporangia) which 

 are usually provided with one or more rhizoid-like appendages. In 

 some species, however, there seem to be no such appendages (e.g., 

 G. arrhiza Hariot). The "sporangia" arise as segments of the branch- 

 ing filaments. These segments enlarge and give off processes, finally 



