PROTOCOCCACE^E. 47 



The family (or coenobiutn) in this genus is solid, and not hollow as in 

 Ccelastrum, composed of wedge-shaped or heart-shaped cells, somewhat 

 compressed and united into globose families, the narrow ends meeting 

 in the centre, with the outer margin emarginate or divided. 



Sorastruni spinulosum. Nag. Einz. Alg. p. 99. 



Ccenobium spinulose, cells wedge-shaped, apex slightly 

 emarginate, angles obtusely rounded, bi-spinnlose. 



SIZE. Ccenobium to '01 mm. diam. 



Archer Micr. Journ., 1866, p. 124. Pritcli. Infus. t. 1, f. 

 56-58. Rabh. Alg. iii, 81. Reinsch Algenflor. p. 86, t. 5, f. 6. 



In stagnant water. 



Plate XIX. fig. 1. #, &, families magnified 400 diameters ; c, side 

 view of cell j d, front view of same. 



GENUS 33. SEX.ENASTRUM. Reinsch. 



Cells semilnnate, joined together by the middle of the convex 

 margin, in families of 4-8, regularly disposed. Propagation 

 unknown. Reinsch Algenflor. Frank. p. 64. 



Selenastrum Bibraianum. Reinsch Algenflora p. 64. 



Cells semilunate, with the cusps either expanded or curved 

 inwards ; minor families constituted of four cells in pairs, major 

 families of these combined in more or less spherical masses. 



SIZE. Cells -016--023 mm. long X '005--008 mm. diam.; 

 minor families '0:23-'031 mm. diam. 



In moor pools. 



Plate XIX. Jig. 3. a, families magnified 400 diameters; b, pair of 

 cells magnified 1000 diameters. 



Sub-Family 9. 



Cells always innate, often distinctly stipitate, variable in 

 form ; cell-membrane delicate, growing thicker with age (then 

 double membrane visible) ; cell-contents bright green, homo- 

 genous, afterwards always granular, with one starch granule, 

 ultimately divided. Propagation by repeated binary division of 

 the cytioplasm, resulting in more or less numerous biciliate zoo- 

 gonidia. Rabh. Alg. Kur. iii. 81. 



GENUS 34. CHARACIUM. Brawn. (1817.) 

 Cells oblong, ovate, pyriform, fusiform, rarely acicular or 

 subglobose, equal or oblique, erect or inclined, attenuated at 

 the base in a hyaline stem. Cell-contents green, homogenous 

 or granular, zoogonidia, succeeding division of the cytioplasm, 

 more or less numerous, occupying the whole of the cell, at 

 length greatly agitated, escaping by a lateral (rarely terminal) 

 rupture, oblong, with two vibratile cilia. Braun Unicel. Alg. 

 p. 29. 



