1885.] 



MICROSCOPICAL JOURNAL. 



73 



20. Genus Tetraspora Agardh. 

 Cells spherical, with thick diffluent 



walls, distributed without order, or 

 in twos and fours, in a large, one- 

 layered gelatinous thallus, originally 

 sac-like, aftenvards open. Walls of 

 the mother-cells after division disap- 

 pear. Cell-contents green, usually 

 with distinct starch-grain. Division 

 in different directions, in the same 

 plane. 



Zoospores with two cilia form 

 singly in the cells. 



21. Genus Staitrogen iaYS\X.7\x\^. 

 Cells of cubical or angular form, 



lying in a plane, united in table-like, 

 free swimming families of 4-8-16 

 cells. Division in two directions, at 

 right angles. 



Propagation by still gonidia. 



22. Genus Inoderma Kiitzing. 

 Cells oblong ; arranged more or less 



in longitudinal series loosely connected 

 with soft gelatin, tegument thick, dif- 

 fluent ; constituting a gelatino-mem- 

 branaceous, irregularly expanded, or 

 pseudo-filamentous thallus. Division 

 in one direction only. 



Propagation by motile gonidia. 



23. Ge.y\Vi%SchizochIamys A.. Braun. 

 Cells globose or ovate, single or 



united in gelatinous families like 

 Tetraspora. Tegument of mother- 

 cell separating in 2-4 equal parts, by 

 splitting into halves or quarters. The 

 pieces remain embedded in the com- 

 mon jelly for a long time. 



Propagation by micro- and macro- 

 gonidia. 



24. Genus Palmella Lyngbye. 

 Cells spherical, with green, red or 



orange colored contents, and thick 

 confluent walls, which produce a 

 structureless, gelatinous layer. Divi- 

 sion in all directions. Thallus with- 

 out definite form. 



[The palmellse are doubtless for the 

 most part stages in the development 

 of higher alg£e.] 



25. Genus Poryhrydhan Nageli. 



Cells spherical or angular from mu- 

 tual pressure, with rather thin difflu- 

 ent, integument, united in families of 

 a single (rarely double) layer of cells. 



Cell-contents red or purple. Division 

 in different directions of the layer. 



[This genus is included among the 

 Rhod.ophyceiE by Rabenhorst, but it 

 is evidently very closely related to 

 Palmella.^ 



d. Stipitat^. 



26. Genus Cos7i7ocladinm Br^bis- 

 son. 



Cells elliptic or kidney-shape, on 

 the ends and axes of dichotomously 

 branched, hyaline stems, the entire 

 family having a tree-like appearance. 

 Cell-contents green, with a starch- 

 grain. Division only in the direc- 

 tion of the stem. 



Propagation by zoospores, 4-8 of 

 which form in a mother-cell. 



[A new genus Hauckia Borzi, is 

 very closely related to Cosmocladijini ; 

 but we are not now able to give its 

 distinctive characters. See Brebis- 

 sonia, 1881, p. 97.] 



27. Genus j\Iischococczisl>i'a.^e\i. 

 Cells globose, terminal, two or four 



in rows on the ends of dichotomously 

 branching, very delicate, hyaline thal- 

 lus. 



Propagation by zoogonidia. 



28. Genus Dictyosphcermm Na- 

 geli. 



Cells elliptic or kidney-shape, with 

 thick, diffluent walls, united in free- 

 swimming spherical, hollow families, 

 single cells on the ends of slender fila- 

 ments which radiate from the centre 

 of the family and repeatedly branch 

 toward the periphery. Cell-contents 

 green, with a starch-granule and a 

 peripheral vacuole. Division at first 

 in all directions, later only radially. 



29. Genus Dimorphococcus A. 

 Braun. 



Cells in fours on very short branches, 

 dissimilar, the two intermediate ones 

 contiguous, oblique, reniform or ob- 

 tuse ovate, the two lateral ones oppo- 

 site and separate, lunate. Families 

 free-swimming, forming boti'yoidal 

 clusters. 



30. Genus Oocardium Nageli. 

 Cells subovate, slightly emargi- 



nate at the ends, stipitate, with cen- 

 tral chlorophyll vesicle, often with a 



