PLATE XXV 



FIGURES 55-57. Calothrix sp. x 500. 



FIGURES 58-67. Nostoc antarctica sp. n. 58, young thalli, nat. size ; 59, fully grown 

 thalli, nat. size; 60, margin of adult thallus showing the dense crowding of the 

 trichomes, x 500 ; 61-65, portions of isolated trichomes showing seriate hetero- 

 cysts, x 500 ; 66, very young thallus, x 500 ; 67, portion of trichome with five 

 spores (sp.}, x 500. 



FIGURES 68-69. Lyngbya shackletoni sp. n. x 500. 



FIGURES 70-71. Lyngbya murrayi sp. n. 70, x 500; 71, x 1000. 



FIGURE 72. Lyngbya erebi sp. n. x 1000. 



FIGURE 73. Phormidium glaciate sp. n. x 1000. 



FIGURES 74-75. Phormidium antarcticum sp. n. x 1000. 



FIGURE 76. Phormidium fragile (Menegh.) Gom. forma tennis, x 1000. 



FIGURES 77-85. Phormidium autumnale (Ag.) Gomont. Various forms, x 500. 



FIGURES 86-90. Oscillatoria producta sp. n. 86, x 500 ; 87-90, x 1000. 



FIGURES 91-94. Oscillatoria subproboscidea sp. n. x 500. 



FIGURES 95-97. Oscillatoria deflexa sp. n. 95, twisted bundle of trichomes, x 100 ; 

 96 and 97, single trichomes, x 1000. 



