1. Duration of service
   - longevity

Type of: longness

• family Hippocastanaceae
• family Hippopotamidae
• family Hipposideridae
• family Hirudinidae
• family Hirundinidae
• family history
• family Holocentridae
• family Holothuridae
• family Homaridae
• family Hominidae
• family Hostaceae
• family Hyacinthaceae
• family Hyaenidae
• family Hydnaceae
• family Hydnoraceae
• family Hydrangeaceae
• family Hydrobatidae
• family Hydrocharidaceae
• family Hydrocharitaceae
• family Hydrochoeridae
• family Hydrophidae
• family Hydrophyllaceae
• family Hygrophoraceae
• family Hylidae
• family Hylobatidae