Subclass Elasmobranchii Bonaparte, 1838 - shark-like fishes Cohort Euselachii Hay, 1902 - spined sharks and relatives see Infraclass Euselachii Hay, 1902 Subcohort Neoselachii Compagno, 1977 - modern sharks and rays see Cohort Neoselachii Compagno, 1977 Order Hexanchiformes Compagno, 1973 - six-gill sharks Family Chlamydoselachidae Garman, 1884 - frill sharks