Family. Genus. No. of Species. Distribution.
1. Argonauta 4 Tropical seas.
2. Octopus 46 Rocky coasts in temperate and
tropical regions.
Section B.--_Decapoda_.
3. Loligo 19 Cosmopolitan.
4. Sepia 30 On all coasts.
5. Spirula 3 All the warmer seas.
ORDER II.--_Tetrabranchiata_.
6. Nautilus 3 or 4 Chinese Seas, Indian Ocean,
Persian Gulf.