Blue tits  (Cyanistes caeruleus) from the Canary islands (circa 1920).
Scanned from Amazing Rare Things: The Art of Natural History in the Age of Discovery
Henrik Grönvold (1858–1940)

Pig skeleton by BioDivLibrary on Flickr.
[Die vergleichende Osteologie /.Bonn :In Commission bei Eduard Weber,1821-1838..biodiversitylibrary.org/page/40170362

Image transferred from uncovered opposite plate.
From p. 289 of Nature Displayed in the Heavens and On the Earth by Simeon Shaw (1823). Original from Oxford University. Digitized July 11, 2008.

Amphisbaena fuliginosa, also known as the Black-and-white Worm Lizard, Speckled Worm Lizard or Spotted Worm Lizard

Leonardo da Vinci A Copse of Trees, 1508

Royal boa. (1802) 
via NYPL

Pollen from ‘Ueber den Pollen’ by Julius Fritzsche Published 1837

1908 Medical Illustration - The Arteries

Happy Birthday to John James Audubon!
The artist was born in Haiti in 1785. He was sent to America in 1803, and lived on the family farm outside of Philadelphia, where he proved that the same birds return to the same nesting sites each year by tying strings around their legs. After 10 years in business—painting all the while as his hobby—Audubon went into the wilderness on an epic quest to paint the birds of American. A few years later, he sailed to England where his work “The American Woodsman” was an overnight success.
via the US National Archives on Facebook »
What is your favorite American bird?

From: ‘Fossil Medusæ’ by Charles Doolittle Walcott. Published 1898

oldbookillustrations: Sphinx Moths (family Sphingidae)

Gynoeryx meander, Batocnema coquerelii, Adhemarius palmeri, Madoryx bubastus, Xylophanes tyndarus.
Poujade, from Histoire naturelle des insectes (Natural history of insects), atlas to volumes 5, 6, 7, by Jean-Baptiste Boisduval and Achille Guénée, Paris, 1836-1858.
(Source: archive.org)