book gill
Zoology
noun
(In aquatic arachnids) any of several pairs of external gills that each contain numerous fine lamellae; also called gill book.
- Now only found in horseshoe crabs, book gills are thought to be ancestral to book lungs..
Origin
Late 19th century.
- care assistant
- care attendant
- careen
- career
- career adviser
- career advisor
- career break
- careerism
- careerist
- careers adviser
- careers advisor
- career structure
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- carefreeness
- careful
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- caregiver
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- care group
- care home
- care in the community
- care label
- careless
- carelessly