Heterotis, [557], [555];

larval gills, [290], [418];

size of eggs, [408];

H. ehrenbergii, gill-helix, [294];

H. niloticus, [556], [558]

Hexagrammidae, [696], [694]

Hexagrammus, [696]

Hexanchus, [443];

branchial clefts, [277];

H. griseus, [443]