A very nice illustration of the social spider Eresus. Most spiders are solitary, but a few of them live in large groups. These spiders are not social like insects such as ants or bees are social, but they do show co-operative hunting and broodcare.
BibliOdyssey had a wonderful post a few days back about this book called the Monograph of Spiders, written by Carl Hahn
Monographie der Spinnen’ was the first ever German monograph on spiders and one of the earliest publications anywhere devoted solely to spiders. Hahn provided the original descriptions of a number of previously unknown spider species together with accurate illustrations, so the work is regarded not only as an important historical scientific document, but is still cited today as a primary source in the field of arachnology.