Yet as systematists their authors were no worse than Klein, whose Historiae Avium Prodromus, appearing at Lubeck in 1750, and Stemmata Avium at Leipzig in 1759, met with considerable favour in some quarters.
Of a very different kind is the next we have to notice, the Prodromus systematis mammalium et avium of Illiger, published at Berlin in 1811, which must in its day have been a valuable little manual, and on many points it may now be consulted to advantage - the characters of the genera being admirably given, and good explanatory lists of the technical terms of ornithology furnished.
Coming to British Indian possessions, and beginning with Ceylon, we have Kelaart's Prodromus faunae Zeylanicae (8vo, 1852), and Ceylon.
At Geneva are three large collections - Augustin Pyrame de Candolle's, containing the typical specimens of the Prodromus, a large series of monographs of the families of flowering plants, Benjamin Delessert's fine series at the Botanic Garden, and the Boissier Herbarium, which is rich in Mediterranean and Oriental plants.
As early as 1721 he was seeking to lay the foundation of a scientific explanation of the universe, when he published his Prodromus principiorum rerum naturalium, and had already written his Principia in its first form.