
1) Arachnid anatomy
Found on
https://www.crosswordclues.com/clue/book-lung

A book lung is a type of respiration organ used for atmospheric gas exchange that is found in arachnids, such as scorpions and spiders. Each of these organs is found inside a ventral abdominal, air-filled cavity (atrium) and connects with the surroundings through a small opening for the purpose of respiration. Book lungs are not related to the lun...
Found on
http://en.wikipedia.org/wiki/Book_lung

form of respiratory organ found in certain air-breathing arachnid arthropods (scorpions and some spiders). Each book lung consists of a series of ... [4 related articles]
Found on
http://www.britannica.com/eb/a-z/b/92

A respiratory cavity containing a series of leaflike folds.
Found on
http://www.earthlife.net/insects/glossary.html

A set of soft overlapping flaps, covered up by a plate on the abdomen, through which oxygen is taken up and carbon dioxide given off. Characteristic of many terrestrial arachnids such as scorpions and spiders.
Found on
http://www.ucmp.berkeley.edu/glossary/gloss7metazoa.html

A set of soft overlapping flaps, covered up by a plate on the abdomen, through which oxygen is taken up and carbon dioxide given off. Characteristic of many terrestrial arachnids such as scorpions and spiders.
Found on
http://www.ucmp.berkeley.edu/glossary/glossary_7.html

[
n] - organ in many arachnids containing many thin folds of membrane resembling the leaves of a book
Found on
http://www.webdictionary.co.uk/definition.php?query=book%20lung

An air-filled cavity, containing stacks of blood-filled leaves, opening on the underside of the abdomen.
Found on
http://www.xs4all.nl/~ednieuw/Spiders/Spiderglossary.htm

the main respiratory organ in many arachnids.
Found on
https://www.amentsoc.org/insects/glossary/begins/with/b/
noun organ in many arachnids containing many thin folds of membrane resembling the leaves of a book
Found on
https://www.encyclo.co.uk/local/20974

a simple type of lung found in spiders and scorpions. Easily seen on the underside of both
Found on
https://www.encyclo.co.uk/local/21561

the respiratory organ of a spider, scorpion, or other arachnid, composed of thin, membranous structures arranged like the leaves of a book.
Found on
https://www.infoplease.com/dictionary/book-lung
No exact match found.