www.biolib.de - online : http://www.biolib.de/
A major collection of historical and classical books on biology and natural history. Most of the works are in German but it includes several with fine illustrations. If you're looking for a specific work, follow the "Authors" link; otherwise "Categories" is a useful starting point.
You can browse on-line or, in some cases, download the entire work as Acrobat (PDF) files.
The site is in German and English. The following translations may help:
|hohe Auflösung ||high resolution|
|neidrige Auflösung ||low resolution|
The more useful items include:
|Reitter, Edmund ||1908-11 ||(Beetles) ||Fauna Germanica; Die Käfer des Deutsches Reiches. ||Vols 1-5|
|Ricken, ||Adalbert ||1915 ||(Toadstools) ||Die Blatterpilze|
|West, W. & G.S. & Carter, N. ||1904-23 ||(Algae) ||A monograph of British Desmidiaceae. ||Vols I-V.|