Museum Victoria has a delightful on-line exhibition, Caught and Coloured, about Frederick McCoy's Prodromus of the Zoology of Victoria.
McCoy established the natural history collection that became the National Museum of Victoria. In 1858, he began his Zoology of Victoria project. Over the next 40 years, artists produced more than a thousand plates covering a range of native fauna. Museum Victoria has reproduced a number of the plates on their site, accompanied by extensive information on the history of the project and the techniques used.
[I'm not sure why their plate of leeches is titled 'slug'. Perhaps they should have checked that one out beforehand. I might send them an e-mail ...]