Carter.— ^Studies on the Chloroplasts of Desmids. Ill . 285 
serial longitudinal sections parallel to the front faces of the semi-cell (s, starch grains of the sheaths 
of the pyrenoids). 
Figs. 50 and 51. C. praemorsum, Breb. Fig. 50, front view; Fig. 51, optical transverse 
section. 
Figs. 52 and 53. C. margaritiferum , Menegh. Fig. 52, front view; Fig. 53, transverse 
section. 
Figs. 54 and 55. C. binum , Nordst. Fig. 54, front view ; Fig. 55, optical transverse section. 
Figs. 56 and 57. C. tetraophthalmum , Breb. Fig. 5 6, front view ; Fig. 57, optical transverse 
section. 
PLATE XII. 
Figs. 58-61:. C. Ralfsii, Breb. x 510. Figs. 58-60, various individuals in front view; 
Fig. 61, transverse section. 
Figs. 62 and 63 C. amoenumpi&xib. x 810. Fig. 62, front view; Fig. 63, optical transverse 
section. 
Figs. 64-6. C. biretum , Breb. x 810. Fig. 64, longitudinal section parallel to front faces 
of the cell ; Fig. 65, transverse section ; Fig. 66, longitudinal section parallel to the lateral faces of 
the cell (contents of lower semi-cell not shown). 
Figs. 67 and 68. C. subcucwnis, Schmidle. x 810. Fig. 67, front view (right-hand chloro- 
plast of lower semi-cell in optical section) ; Fig. 68, optical transverse section. 
Figs. 69 and 70. C. reniforme , (Ralfs.) Arch, x 810. Fig. 69, front view (right-hand 
chloroplast of upper semi-cell in optical section) ; Fig. 70, optical transverse section. 
Figs. 71 and 72. C. pachydermum , Lund, x 810. Fig. 7 r, front view; Fig. 72, optical 
transverse section. 
Figs. 73 and 74. C. cucumis, Corda, x 810. Fig. 73, front view; Fig. 74, optical longi- 
tudinal section. 
PLATE XIII. 
Figs. 75-81. C. Brebissonii , Menegh. x 810. Fig. 75, front view ; Fig. 76, longitudinal 
section ; Figs. 77 and 78, optical transverse sections of the two semi-cells of an individual having 
very scanty chloroplasts ; Figs. 79-8 L transverse sections of various individuals. 
Figs. 82 and 83. C. ovale, Ralfs. x 510. Fig. 82, front view; Fig. 83, optical longitudinal 
section. 
Figs. 84 and 85. C. Askenasyi , Schmidle. x 510. Fig. 84, front view; Fig. 85, optical 
transverse section. 
Figs. 86-8. C. controversum, West, x 810. Fig. 86, front view ; Fig. 87, optical transverse 
section ; Fig. 88, optical longitudinal section. 
