FIGURES 17–19. Hassallia littoralis TEM images. Fig. 17. Hormogonia formation through a necridic cell. Fig. 18. Young isopolar hormogonium with a wide stratified sheath. Fig. 19 in Hassallia littoralis sp. nov. (Cyanobacteria, Microchaetaceae) from Mexico's marine supralittoral based on morphological and molecular evidence - González-Resendiz, Laura (2013)