“ To make his work as trustworthy as possible Dr Zittel made special studies of each great group, commencing with the fossil sponges, on which he published a monograph (1877-79) . In 1895 he issued a summary of his larger work entitled Grundzüge der Palaeontologie (ed. 2, part 1, Invertebrata, revised by Dr Zittel in 1903; the American edition of 1900 by C. R. Eastman is so revised, sometimes in opposition to Zittel's views, as to be practically an independent work) . ”

“ In 1880 he was appointed to the geological professorship, and eventually to the directorship of the natural history museum of Munich. His earlier work comprised a monograph on the Cretaceous bivalve mollusca of Gosau (1863-66) ”