12th edition of Systema Naturae

Only five editions of Systema Naturae were written by Linnaeus himself, namely the first, second, sixth, tenth and twelfth.

[6] Volume 2 covered Regnum Vegetabile – the plant kingdom; it comprised 736 pages and appeared in 1767, with an additional 142-page Mantissa Plantarum.

[10] The 12th edition also included the hundred insect species published separately in Centuria Insectorum,[2] and omitted a claim which Linnaeus had made in earlier editions, that new species do not form,[11] implicitly allowing speciation.

Also, on the last page of the book, Linnaeus added a new genus he named "chaos" in order zoophyta, class vermes.

In fact, chaos infusorium included every known protist of the 18th century (except volvox, that was divided into his own genus).